<META name keywords>

Description:

The purpose of the keywords Metatag is to inform the spider or search engine of the main topics or points of a document. Due to extreme misuse of this Metatag it's relevance in many search engines has been downgraded. Keywords in the tag should also appear within your content, description, title, alt tags and elsewhere within your document to be considered by the search engines.

Here are some good rules of thumbs when using keywords.

Limit keywords to under 1,000 characters.
Do not repeat keywords more than 3 times.
Use plural keywords.
Don't repeat keywords hundreds of times in the Metatags, alt tags, description and text.
Include misspellings and different cases.
Use only the Metatags that make sense for your document.

Attributes:

<meta name="Keywords" content="text">
	"Text" is the list of keywords. You may comma separate or not. Some people claim it is better to do so, and some claim it is not.

Examples:

<meta name="keywords" content="HTML, hypertext, markup, language, web, pages">

This tag defines the keywords for the document.