Attributes are another important part of HTML markup. An attribute is used to define the characteristics of an element and is placed inside the element's opening tag. All attributes are made up of two parts: a name and a value:
- The name is the property you want to set. For example, the <font> element in the example carries an attribute whose name is face, which you can use to indicate which typeface you want the text to appear in.
- The value is what you want the value of the property to be. The first example was supposed to use the Arial typeface, so the value of the face attribute is Arial.
The value of the attribute should be put in double quotation marks, and is separated from the name by the equals sign. You can see that a color for the text has been specified as well as the typeface in this <font> element:
<font face="arial" color="#CC0000">
Many HTML tags have a unique set of their own attributes. These will be discussed as each tag is introduced throughout the tutorial. Right now we want to focus on a set of generic attributes that can be used with just about every HTML Tag in existence.
The four core attributes that can be used on the majority of HTML elements (although not all) are:
The id Attribute:
The id attribute can be used to uniquely identify any element within a page ( or style sheet ). There are two primary reasons that you might want to use an id attribute on an element:
- If an element carries an id attribute as a unique identifier it is possible to identify just that element and its content.
- If you have two elements of the same name within a Web page (or style sheet), you can use the id attribute to distinguish between elements that have the same name.
We will discuss style sheet in separate tutorial. For now, the id attribute could be used to distinguish between two paragraph elements, like so:
<p id="html">This para explains what is HTML</p> <p id="css">This para explains what is Casecading Style Sheet</p>
Note that there are some special rules for the value of the id attribute, it must:
- Begin with a letter (A.Z or a.z) and can then be followed by any number of letters, digits (0.9), hyphens, underscores, colons, and periods.
- Remain unique within that document; no two attributes may have the same value within that HTML document.
The title Attribute:
The title attribute gives a suggested title for the element. They syntax for the title attribute is similar as explained for id attribute:
The behavior of this attribute will depend upon the element that carries it, although it is often displayed as a tooltip or while the element is loading.
|<h4 title="Hello HTML!">Titled Heading Tag Example</h4>|
Above code will generate following result:
Titled Heading Tag Example
Now try to bring your cursor over "Titled Heading Tag Example" and see the result.
The class Attribute:
The class attribute is used to associate an element with a style sheet, and specifies the class of element. You learn more about the use of the class attribute when you will learn Casecading Style Sheet (CSS). So for now you can avoid it.
The value of the attribute may also be a space-separated list of class names. For example:
class="className1 className2 className3"
The style Attribute:
The style attribute allows you to specify CSS rules within the element. For example:
<p style="font-family:arial; color:#FF0000;">Some text...</p>
There are three internationalization attributes, which are available to most (although not all) XHTML elements.
The dir Attribute:
The dir attribute allows you to indicate to the browser the direction in which the text should flow.The dir attribute can take one of two values, as you can see in the table that follows:
|ltr||Left to right (the default value)|
|rtl||Right to left (for languages such as Hebrew or Arabic that are read right to left)|
<html dir=rtl> <head> <title>Display Directions</title> </head> <body> This is how IE 5 renders right-to-left directed text. </body> </html>
When dir attribute is used within the <html> tag, it determines how text will be presented within the entire document. When used within another tag, it controls the text's direction for just the content of that tag.
The lang Attribute:
The lang attribute allows you to indicate the main language used in a document, but this attribute was kept in HTML only for backwards compatibility with earlier versions of HTML. This attribute has been replaced by the xml:lang attribute in new XHTML documents.
When included within the <html> tag, the lang attribute specifies the language you've generally used within the document. When used within other tags, the lang attribute specifies the language you used within that tag's content. Ideally, the browser will use lang to better render the text for the user.
The values of the lang attribute are ISO-639 standard two-character language codes.Check HTML Language Codes: ISO 639 for a complete list of language codes.
<html lang=en> <head> <title>English Language Page</title> </head> <body> This page is using English Language </body> </html>
The xml:lang Attribute:
The xml:lang attribute is the XHTML replacement for the lang attribute. The value of the xml:langattribute should be an ISO-639 country code as mentioned in previous section.
Here's a table of some other attributes that are readily usable with many of HTML's tags.
|align||right, left, center||Horizontally aligns tags|
|valign||top, middle, bottom||Vertically aligns tags within an HTML element.|
|bgcolor||numeric, hexidecimal, RGB values||Places a background color behind an element|
|background||URL||Places an background image behind an element|
|id||User Defined||Names an element for use with Cascading Style Sheets.|
|class||User Defined||Classifies an element for use with Cascading Style Sheets.|
|width||Numeric Value||Specifies the width of tables, images, or table cells.|
|height||Numeric Value||Specifies the height of tables, images, or table cells.|
|title||User Defined||"Pop-up" title for your elements.|
We will see related examples as we will proceed to study other HTML tags.