The meta keywords tag allows you to provide additional text for crawler-based search engines to index along with your body copy.The meta keywords tag is sometimes useful as a way to reinforce the terms you think a page is important for ON THE FEW CRAWLERS THAT SUPPORT IT. For instance, if you had a page about stamp collecting -- AND you say the words stamp collecting at various places in your body copy -- then mentioning the words "stamp collecting" in the meta keywords tag MIGHT help boost your page a bit higher for those words.Remember, if you don't use the words "stamp collecting" on the page at all, then just adding them to the meta keywords tag is extremely unlikely to help the page do well for the term. The text in the meta keywords tag, FOR THE FEW CRAWLERS THAT SUPPORT IT, works in conjunction with the text in your body copy.

1. Each keyword should be separated by a comma. Capitalization is not important in the keyword meta tag.
2. The meta-tag keywords attribute
   When selecting words to place in the meta-tag keywords attribute, you must select keywords that accurately reflect the content of the web page. If a word appears in your meta-tags that does not appear in your main body content, then your web page will very likely receive a spam penalty from the search engines, possibly getting your web site permanently removed from the search engine databases.
3. Singular vs. plural--When creating your keywords list, place the version of the keyword that your site visitors use the most at the beginning of your keyword list.
4. Uppercase vs. lowercase--Most search engines do not use case sensitivity as an element of their algorithms. Thus, using all versions (all uppercase, all lowercase, initial capitalization) of keywords and keyword phrases is probably a waste of time and can result in a spam penalty for keyword stacking.
5. Commas vs. no commas--It makes no difference to the search engines that use the meta-tag keywords attribute whether or not you use commas or spaces to separate your keywords and keyword phrases. If it is easier for you to view your keyword phrases with commas, then use them. Using commas will not affect your web page's relevancy.
6. Misspelled keywords--Since some keywords are commonly misspelled (such as the word "millennium"), you might want to put a misspelled keyword in your meta-tags. However, if that misspelled word does not appear in your main body text, this strategy is a waste of time. Search engines use both keyword frequency and keyword placement in their algorithms. If you are putting a misspelled keyword in only one place (i.e., your meta-tag keywords attribute), it's not helping your web page's relevancy because the keyword concentration for that one word is practically non-existent.