Metatags are the Page title, Description and Keywords that appear in the <HEAD> part of your page. They are used by search engines to help define the content of your page and can also be used in the displayed descriptions for your pages in search results.
They have become less important as search engine algorithms have become more sophisticated but they are still widely used and there is nothing to be lost by having them properly set up and relevant to your page content - preferably customised for each individual page.
We use a programme called Win Web Crawler to spider our own site and extract the metatag content. It is saved as a .csv file that we then format in Excel for review. Apart from allowing us to check the metatag content, it is a great check that our site is fully spiderable by search engines.
We also us the crawler to look at competitor websites or sites in complementary product areas to see if their information gives us any good ideas for development of our own site.
Here is a good article about metatags and how they are used
||Is displayed at the top of the browser in the header bar and often used as the page title and link text in search engine results
||Helps define content, sometimes used as page description in search engine listings
|Helps define content, sometimes used as part of weighting algorithm in search engine page ranking
This is how the metatags for this page have been set up in the html
Win Web Crawler: A Powerful Web Crawler Utility for Windows.