XHTML by Example

Meta Information—The Document Head

Some of the most important information in your XHTML documents will be included before you begin to create what we traditionally think of as the "content." This section is made up of at least five components: the DOCTYPE declaration, and the html,head,title, and meta elements. Each of these tags provides a discrete piece of information about your document, and as such, is often referred to as metadata. Defined simply, metadata is data (information) about data. So metadata in your XHTML documents will be information about your document.

Of the five tags that provide meta information, four of them are required in all XHTML documents. The first required element in any XHTML document is the DOCTYPE declaration. ...