Meta Tags - An Important Part of Every Web Page
Meta tags are mandatory from a search engine optimization perspective, there are several mistakes that may be made by excluding these as well as attempting to 'spam' the SE's with them so heres an instant summary of the three main ones:
Meta Page Title Tag
The title tag is supported by all se's and should be looked at as the utmost important aspect in your optimisation process. How come this you might ask? Well the page title may be the first thing internet search engine spiders and human visitors will dsicover. Your title appears near the top of the page in the browser and the title also becomes the clickable link in the search engines like google and really should therefore be concise, accurate you need to include your keywords.
Meta Description Tag
The meta description tag is supported by the majority of the search engines, it isn't as important because the Title Tag as the website viewer won't see it however the description may also be found in the search listings beneath the title tag and therefore should be a precise and keyword driven description of what the page value is. Google usually uses an abstract of the page content and can utilize the description tag only when it cannot find enough on page content to create a full page description.
Meta Keywords Tag
Due to massive abuse this tag is quite rarely useful however in my estimation should be used. Include your primary keywords in here but usually do not go crazy, 4 or 5 is plenty of usually. It really is far better to add your keywords in the on page copy and can hold better weight with the SE's therefore. Please remember however that it still must read well to the eye.