While using meta tags it is best to be aware of testing results for these meta tags. You can then understand them in depth. You can know more about meta tags testing results at http://www.webmarketingnow.com/tips/meta-tags-uncovered.html

The meta title tag is not very useful. It is better to use the title tag. You can find tested information on the meta title tag at http://www.webmarketingnow.com/tips/meta-title.html

The meta expires tag gives uncertain results. Therefore it makes sense to test the meta expires tag. You can see meta expires tag test results at http://www.webmarketingnow.com/tips/meta-tags-meta-expires.html