Meta Tags are

• A means to give a search engine some idea about the nature or thrust of a document. This was before the S.E.'s had the financial, software and hardware resources to crawl entire documents.
• The phrase meaning hidden tags
• Situated in the head section of page ..... in the source code
• Still used by some engines, and not by others, leading to years of debate on their worth
• Often, where the pages description is pulled from.......so this may be used on the S.E.R.P.s, if it exists

It looks something like the following for a standard html page;

The "Meta nam="generator" bit, has little use other than to give credit to the program which did the generation. If done by yourself, with the likes of Notepad, Word pad or other editor;  this can be ignored completely.

The important stuff in this context, are the title, content, description,  keywords and robots tag.

Evolving from the image above, we get something like this;

Content Type.

The image of the meta tag above, is for the benefit of browsers such a Internet Explorer, Firefox, etc., to give them some idea of how to handle various characters within a particular standard. Nothing really to do with seo, once the page displays in a reasonable way.

         Description tag.

As mentioned already, a search engine may use whatever you place inside this meta data, on their search engine result pages (S.E.R.P.'s ). So what is inserted in this tag, may influence  a surfer or differentiate your page from the others. Get to the point, and include relevant keywords, sparsely.

Keywords tags.

Usually seperated by commas as de-limiters, which basically indicate to an S.E.  that a phrase is seperate to a word. Use keywords only if they apply to the document and relevance is the key. As meta tags carry less importance with some of the main engines, there is no point in overdoing, spamming or black-hatting this tag.

Robots.

The first on-page means of limiting spiders and only if they comply!  It can be of the form in the image already shown or in other forms which depend on doc types, such as the following;

The important factor is whether you choose for the page to be followed or not. If you wanted to change this to

then a directive is given in the hope that search engines will neither index the contents of a page, or follow links which may be on it. This is not a directive to block entry.

Anyway, there is a basic meta tags generator which can be used online at http://www.rankquest.com/tools/Meta-Tag-Generator.php