I'm quite often asked why I use a gif for one thing and a jpeg for another, so I thought I would briefly explain it here to share with everyone. It is important to get these right when managing your content. There are valid reasons for using different file types. There are far too many to list in full, so here are a few of the most common ones:
Gif The gif (Graphical Interchange Format)file is often used in web design as it offers a good quality image at a small file size. It can contain up to 256 'indexed' colors. The colors are called 'indexed' because they may be specifically selected. High detail images are probably better with a Jpg. GIF images can also be animated and saved as "animated GIFs," which are often used to display basic animations on websites; they may also include transparent pixels, which allow them to blend with different color backgrounds; however, pixels in a GIF image must be either fully transparent or fully opaque. Partial transparency is not universally supported by web-browsers yet.
Jpg or Jpeg The Jpg (Joint Photographic Experts Group) are commonly used for storing digital photos since the format supports up to 24-bit color (millions of colors!!: the number is actually 256 X 256 X 256) unlike gifs which only support up to 256 colors in total; also a common format for publishing Web graphics. Jpg are not good at being compressed - they will dramatically loose quality, a trait known as lossy.
Png The Png (Portable Network Graphic) is a common web file. It is often used because the image loads in quality, rather than in stages. This means that the image will appear from the offset on the web page will gradually load. Like jpg, millions of colors are supported, and, as such, the Png is often used for higher quality images; however, like gifs, its color may (or may not) be indexed. This is a useful quality when the designer wishes to limit the filesize. It has the unique ability of supporting as many as 16million+ colors, or as few as 2. In addition, this file type may support animation as well as transparency.
Carter-
- TOPICS: You will be quizzed over this material in week 4.
- HOMEWORK: Answer the questions below as you read through the material as the homework for this week's class. You must type both the questions and the answers. If you are able to do so as a page of HTML, I will give you extra credit.
- QUESTIONS: Here are some questions to help guide you through this weeks' material:
- What type of computer application (program) is necessary to view a web-page?
- What type of basic computer application (program) is necessary to TYPE or CREATE a web-page?
- What does the abbreviation HTML stand for?
- What does the abbreviation HTTP stand for? Where do you usually find it?
- What are the individual pieces of code called in HTML?
- What are the first and last tags typed in a web-page?
- What are the two (2) parts of most web-pages?
- What are the three (3) types of HTML tag discussed in Wednesday's class? What is the main difference among them?
- What are attributes used for?
- What are some examples of block tags? What are some examples of inline tags?
- Which tag is the anchor tag? What is the attribute that goes with it to create a hyperlink? What is hypertext?
- What does the abbreviation XHTML stand for?
- Describe what XML is?
- What is the difference between XHTML and conventional HTML?
- What are some of the standards that should guide the typing of strict XHTML?
- What does CSS stand for? What is it used for?
- What is the difference between XHTML and CSS?
- What is an empty tag? What are some examples of empty tags?
- What attribute must be used with the <img/> in order to place an image into a web page?
- INTRODUCE--XHTML and the Internet:
- General Information:
- XHTML: is an abbreviation for eXtensible HyperText Markup Language, and is not a separate language from HTML. Instead, it is a variation, much like the difference between the language that you use to write an essay for your English class and street slang. The primary differences is that it has stricter standards than conventional HTML. It is actually an attempt to marry the standards for XML (eXtensible Markup Language) to the purpose of HTML, creating web pages. XML is a cross-platform markup language, used primarily for organizing the information in databases. However, since some devices (such as wireless devices) cannot run web-browsers to display the data and information of databases stored on servers, conventional web-pages (created with HTML) may not be displayed on them. HTML is the markup language used specifically for web browsers on ordinary laptop and desktop computers, not for smaller handheld devices. XML has very rigid standards of construction and organization. Therefore, as a way to merge the two mark-up languages, and as a way to prepare for the day when all browsing will be done with XML (so as to make all web-pages cross-platform), stricter standards were created for HTML. Thus the formation of XHTML. As the standards had been, HTML standards are actually quite loose and forgiving. It is possible to make many mistakes and even leave out some tags when typing HTML and still have the web-browser translate the code and present it correctly. This is unreliable, however, as the composer of the code never knows what might come out as a result of the mistakes. Fortunately, web-browsers can decode both HTML and XHTML equally as if there were no difference between them. XHTML, comparatively, has much more rigid standards, and those are the standards that we will use for the creation of our web-pages in this class: The internet is a network or ‘web’ of interconnected devices, such as home computers, that store and exchange information via the phone lines, other types of cables—DSL or Cable, or wireless communications (radio waves).
- The world wide web is one feature of the internet in which information is shared and exchanged between home computers and more powerful devices used primarily for storage known as servers. Its primary mode of exchange is via HTML, Web Browsers, and their related technologies.
- A web browser is a computer application (a ‘program’), such as Netscape Navigator and Internet Explorer, that permits the exchange and transfer of the information displayed on a web-site from one machine (the server where it is stored) to another machine (the home computer of the individual interacting with the website). When a person opens up a particular web-site, the information on it is automatically downloaded into his/her computer, where it is temporarily saved in a folder known as the cache. In this way, the information on an external website is transferred directly into his/her home computer’s hard drive.
- The information that we view on a web-site with our web browser is known as hyptertext, and it is created with a language known as HTML (HyperText Mark-up Language) . HTML is a special coded language that is combined with regular language (regular text such as that which you are reading here on this page). When you view this mixture of languages with a web-browser such as Internet Explorer, the regular text is visible, but the code is rendered invisible. In this way, the web-browser application translates or decodes the information for us and presents it in such a way that we may easily comprehend and enjoy.
- Web-browsers utilize a special method of information transfer when they display web-pages and web-sites. Since hypertext is the combination of ordinary text and HTML that makes up all web-pages, this type of information transfer is called HyperText Transfer Protocol otherwise known as http. There are other types of information transfer (protocols), and one other type you may have seen is known as ftp, or File Transfer Protocol. This one is used primarily for the download of large files such as whole applications like when you go to the Macromedia site to download a trial version of Flash or Dreamweaver.
- Together, the protocol and the web address are known as the url (Uniform Resource Locator). The particular protocol always precedes the web address of a particular web-site or web-page, for example:
http://www.yahoo.com
The http tells us what sort of transfer will occur and what kind of information will be transferred (hypertext—a mixture of ordinary text and HTML). The particular web address tells us which document we will transfer, or download, into our computers to view and read. - A text editor is a computer application, such as Notepad for PC’s or TextEdit for Macs. Such applications’ only use is to create and edit plain text, text without any kind of formatting information (styling such as bold, underline, color, tables, tabs and indents, etc). Plain text, or code, is all that is necessary to create a hypertext; therefore, a text editor will be used to create HTML documents, and a web-browser will be used to view them.
- HTML is a computer code composed of a finite series of individual terms known as tags. These tags may be a single letter, a whole word, or an abbrieviation, but they are always surrounded by angle brackets as such: <html>. They give formatting or organizational instructions for the web-browser to decode and carry out on the presentation of the web-site. The overwelming majority of tags come in pairs, each with an opening tag— <html>, and a closing tag— </html>.
- Basic Structure:
- The <html> tag indicates to the browser the extents of a web document: it is its beginning and ending limits. When the web-browser ‘reads’ a page of hypertext, it should encounter this as the first tag before any others so that it may decode the page properly. In this way, it ‘marks’ the beginning of the document. Likewise, it should also ‘mark’ the end of the document (this is why it is called a markup language); therefore, the last thing that the browser should read is the second tag of the pair, marking the end of the document. As all HTML tag pairs, the second tag is identical to the first, aside from one difference, a backslash that precedes the term: </html>.
- All HTML documents consist of two discreet parts. The first part, indicated by the <head> tag, is always known as the head section. Like the <html> tag, the <head> tag comes in pairs, and so the pair follows the same pattern as the <html></html> tag pair. Therefore, the </head> marks the end of the head section. The information that comes in between this tag pair is primarily information about the document, information such as who wrote it, when it was written, what sort of codes and languages are used, what are some of the main topics and main subject matters of the document, etc. It may also contain additional information that aids in the presentation and interactivity of the document such as stylesheet information, and interactive script information.
- The <title> tag, is the single most important element of the head section. The title of the document itself follows the first title tag, which, in turn, is followed by the second of the tag pair, such as:
<title>My First HTML Document</title>
As mentioned, the first tag of the pair marks the beginning of the title, and the second of the tag pair marks its ending. - Also mentioned, there are two parts to all HTML documents, and in most of them the second part is known as the body section. As the head section contains information about the document and aiding the document, the body section contains the information of the document itself—all of the primary content of the document, the text, the images, the animations, the links, etc. All content belongs between the <body> tag pair. If nothing is typed between the two body tags, then when the document is displayed in the web-browser, it will be entirely blank.
- Block Tags:
- The content of the body is organized by a series of html tags known as block tags. Block tags are a distinct set of tags used to organize information into discreet blocks. Although they do change the size and appearance of text in the page, their primary purpose is NOT to do this. They are NOT intended to format the appearance of the page. As such, they are NOT about presentation (the look of the page) but instead about organization (the structure of the information). This means they are meant to organize and indicate a heirarchy of the information: what is most important, what is secondary in importance, what is tertiary in importance, and so on. There are seven main levels in the HTML heirarchy of organization of textual information: six levels of headings and subheadings, and one level of ordinary paragraph text. Block tags separate blocks of information by blank spaces above and below. Other block tags will be discussed in the future.
- Headings Tags mark out the document's headings and sub-headings. The primary heading of your document will always be marked by the <h1> tag pair, secondary headings by the <h2> tag pair, tertiary headings by the <h3> tag pair, and so on down the hierarchy to the <h6> tag pair, which marks any sub-heading of the least significance. All headings’ tags separate the heading text by a blank space below. It further distinguishes the text by making it bold and changing its size depending on its importance, the more important is larger, the lesser is smaller. It is not necessary to utilize all six headings. They are to be used only when required.
- The <p> tag pair marks an ordinary block of paragraph text. One tag marks the beginning of a paragraph, and the second marks the end of the paragraph. Paragraph text is never bold and never more than 10 or 12pt in size, but each paragraph is separated by a blank space above and below.
- Inline Tags:
- Apart from block tags, inline tags are a second distinct set of tags. With them, the look of the textual content of the body may be modified to a rather limited basis. Unlike the block tags, this group of tags is NOT concerned with organization of information. Rather, they only concern the presentation of the information, the way it appears to us. These tags may italicize the text, underline it, make it bold, change its size, the typeface or the color of the text. Most importantly, the key feature of HTML, what actually makes it hypertext (the links), is achieved with a particular pair of in-line tags. The most significant characteristic common among all in-line tags, however, is that they do not mark out blocks of text. In other words, they do NOT add space above and below the text when you open and close the tag pair.
- The <u> tag pair is an in-line tag that when used underlines text. A single letter, a series of letters, a whole word or groups of words, or even entire sections of text may be set off with this tag to underline it when viewed in the browser.
- The <i> tag pair is an in-line tag that when used italicizes text. A single letter, a series of letters, a whole word or groups of words, or even entire sections of text may be set off with this tag to italicize it when viewed in the browser.
- The <b> tag pair is an in-line tag that when used bolds text. A single letter, a series of letters, a whole word or groups of words, or even entire sections of text may be set off with this tag to bold it when viewed in the browser.
- The <font> tag pair is an in-line tag that when used alone doesn’t do much of anything. A single letter, a series of letters, a whole word or groups of words, or even entire blocks of text, however, may be set off with this tag to alter its appearance it when viewed in the browser. One or more of three attributes must also be used with this tag in order for any modifications of the text to take place: the color attribute changes the color of the text; the size attribute changes the size of the text, and the face attribute changes the typeface.
- The <em> tag pair is an in-line tag that is used to give emphasis; however, unlike the <b> tag pair or the <i> tag pair, the way this tag applies emphasis to a word or phrase is not specific. What the hell does that mean, you may ask. Well, consider this: the <b> tag pair applies emphasis by making text bold. Similarly, the <i> tag pair applies emphasis by italicizing text. That all seems logical.
&nsbsp; The <b> tag pair does not operate in the same way. Instead, it allows the web browser application (Explorer, Firefox, Safari, etc.) to determine what emphasis means and how to change the text. It may interpret it as bold, it may interpret it as italics, it may make the text larger, or it may make it both bold and italics; however, most browsers simply make the text bold. What is good about this, you may inquire next. The advantage to this sort of relative tag is that it leaves the DESIGN aspects of the page up to the DESIGNER. When you learn CSS, you will be able to change what such tags as the <em> tag pair does. If you want to have it make text red, or have it make text with a box around it, or have it make text with a different font, or some combination of those things, you will be able to do that.
Inline tags like the <em> tag pair are the preferred type of tag as opposed to the <b> tag pair and the <i> tag pair. Those tags are DEPRECATED, which is a fancy way of saying that their use is frowned upon. Eventually, they will be phased out of use.
- The <strong> tag pair is an in-line tag that is also used to give emphasis. Much like the <em> tag pair, however, just how that emphasis is applied is up to the designer. You will eventually learn how to customize these tags to make them modify text in whatever way you desire.
- Hyperlinks: The <a> tag pair is a very special in-line tag known as the anchor tag, but when it is used alone without any attributes, it does little or nothing. As a result, an attribute must accompany this tag, and the most common attribute used with it is href which means hypertext reference. This tag and attribute is what distinguishes HTML. It is what defines HTML and allows a user to connect to a seemingly endless array of documents, to go from one site to another with a click of the mouse. A single letter, a series of letters, a whole word or groups of words, whole sections of text, or even images may be set off with this tag and attribute to turn it into a clickable link to another document. It follows the same format as other tags and attributes: format: <tag term attribute = "value"> example: <a href = "put a URL here">
- Empty Tags: Last week there were two types of tags mentioned, block tags, and inline tags. To review, the task of block tags is to organize information into categories. There are seven categories, six levels for headings tags and then for ordinary paragraph text. These seven categories serve to set off text into distinct blocks according to how important it is.
Inline tags make up the other set of HTML tag. As noted, they serve primarily for presentation rather than organization, and therefore are concerned about the look of the text. So, whereas the block tags create blocks, the in-line tags distinguish text within these blocks with various colors, typefaces, sizes and other factors that modify appearance.
There is a third set of tags, however, known as empty tags. These tags are called empty because they do not format content. All other tags surround text or other content: one tag goes in front of the content (or text) and the second tag goes at the end, where one marks the beginning and the other marks the end. Empty tags do not operate in this way. They do not surround content because they do not come in pairs. They are singular tags and as a result are considered empty. Furthermore, they do not surround content but rather generate it, or create it. One empty tag creates a vertical blank space in a web-page, another draws a horizontal line, while yet another creates an image.
- The<br/> tag is one example of an empty tag, and it also known as the break tag . It creates a specific kind of content. It does not create text characters, but rather it creates a blank character, also known as a breaking space. It is called a breaking space because it breaks the line and starts anything that follows back at the margin on the next line. Many of these tags may be used together to create multiple breaking spaces, or to push content further down.
- The<hr/> tag is another example of an empty tag, otherwise known as the hard rule tag . It creates a specific kind of content, not text nor spaces, but a horizontal line across the page. This tag may be modified by three attributes:
- size which alters the thickness of the line;
- width which sets the distance of the line extending across the web-page; and
- color which, obviously, changes the color of the line. Like the bgcolor attribute for the <body> tag, and the color attribute for the <font> tag, the color is set using the Hexadecimal Color Code.
- The<img/> tag is the third example of an empty tag (there are still others), otherwise known as the image tag. It creates a specific kind of content, not text, spaces, or lines, but an image. However, alone this tag does nothing other than indicate to the browser where the image should go (before some bit of text and after some other bit of text, for example). It does not tell the browser which image to put there. In order to do that, an attribute must be used that indicates which image file from your set of folders is to be drawn into the web-page. This attribute is the src attribute, or source attribute. For the value of this attribute, you must type three (3) things:
- the location of the file (usually the images folder within the main folder;
- the name of the file (typed without spaces); and, followed by
- the 3 or 4-letter file extension .
- Attributes: Sometimes additional terms, known as attributes, must be used together with tags. In fact, all HTML tags may be modified and extended with such additional terms, extending their capabilities in order to encompass additional tasks. These terms are placed between the angle brackets after the initial tag term in the first tag of a tag pair. Also, at times there may be more than one attribute per tag, but the order that they are typed is irrelevant. A common attribute of the block tags is align which sets the alignment of the content of the particular block. A common attribute of the <body> tag is bgcolor which sets the background color of the entire page. Tags and attributes always adhere to the following format: format: <tag term attribute = "value"> example: <h1 align = "center">
- XHTML Standards:
- All tags and their attributes must be typed in lower case;
- Quotation marks must surround the values for all attributes;
- Units must be supplied for all attribute values where necessary;
- All tags must be closed and typed in pairs—except in the case of open tags such as <img/> and <br/>
- All empty tags must be typed in the XHTML format with the closing slash before the second angle bracket;
- Some conventional HTML inline tags are deprecated. This means that these tags are not considered a legitimate part of the language and are not to be used if strict standards are being followed. The primary reason for this is that CSS is preferred and can perform all of the same functions more efficiently and with greater flexibility
- A doctype (DTD) indicator must be present at the start of the document. For this reason, if you make mistakes when typing XHTML, the browser will likely not register them, and your page will still be rendered properly. Nonetheless, you would still not be typing XHTML (just standard HTML), and your code would not be able to undergo any scrutiny by an XHTML code validator (see: http://validator.w3.org).
- CSS: otherwise known as Cascading Style Sheets, is not a programming language, and neither is it a mark-up language (as is HTML). It is a series of formatting indications made to a web-browser. When the browser reads these specifications, it carries them out on a particular web-page or set of web-pages. For this reason, the tags—primarily some of the in-line tags—that have mostly to do with formatting, are considered deprecated. This means that they will eventually be eliminated and no then longer considered part of the code. Some of these deprecated tags are <b>, <i>, <u>, and <font>. CSS is a much more efficient way to accomplish the tasks that these tags once did, as most of the styling is centralized in a couple of locations, either in the head of a document or in a separate document altogether devoted solely to CSS, instead of being dispersed throughout the various bodies of documents. Moreover, much more styling and formatting can be accomplished with CSS than standard HTML was ever capable of. code tasks: XHTML—organization and structure of data in a web page. CSS—presentation and aesthetics of the data in a web page.
- General Information:
No comments:
Post a Comment