Meta tags are one of those rather mysterious and arcane HTML elements of a Web page. It also doesn't help that they remain invisible to users, so in most cases no one even knows they were there. One of the principle issues with meta tags is the lack of standard usage. Generally there is no right or wrong way to declare them, so it becomes a confusing matter to many Web designers. In most cases page designers just relegate the task to the product they use to create the pages and leave it at that.
Meta tags may not get much respect, but in fact do have a certain amount of importance. Going by strict interpretation, a page's meta tag is description of that page. It is not meant to be a part of the page content, instead it is an addition to the page describing the content. For example, the Description meta tag is generally meant to provide a synopsis for the page, such as:
The Keywords meta tag on the other hand would contain important keywords used in the Web page, much like an index. For example:
This type of meta tag which generally consists of a name and content sections, is what I would call a descriptive meta tag. Other descriptive meta tags could contain copyright information, author's names, or disclaimers. In other words, descriptive meta tags can be anything you want to convey about the page. It is up to the client side (such as a browser or a spider) to understand and digest them.
In recent years, descriptive meta tags have gained some attention as an SEO (search engine optimization) tool. The idea is that while a search engine robot is crawling a site, the meta tags can help the search engine better categorize and catalogue the pages, possibly helping it achieve better ranking. The fact is that some search engines may give a cursory attention to the descriptive meta tags, but many, such as Google, are rumored to be ignoring them altogether due to excessive abuse by search engine spammers. However, it is possible that descriptive meta tags that attempt to fool search engines, might actually damage the page's ranking or get it banned completely.
The other class of meta tags is what I would call instructive meta tags. These meta tags are used to instruct the browser to take an action, much like instructions sent by a Web server via HTTP headers. They are useful for occasions when a page designer does not have access to the server configuration, or the know-how to make the changes at the server level. Instead these meta tags are used to simulate instructions or information sent by the server in the header area. These are the http-equiv class used for purposes such as caching, MIME declarations, robot instructions, or redirections. For example the meta tag:
Instructs the browser to redirect to the specified URL after 10 seconds.
The meta tags of a Web page can be viewed by simply inspecting the HTML source of that page, generally by clicking on "View Source" from a browser's menu. They are usually found embedded in the <head> section of a Web page. There are also online tools available that can extract the meta tags from a Web page and display them in a concise manner. One such tool can be found at: