Meta tags are a great way to boost your SEO effectiveness, but they are by no means the ultimate solution for those looking to boost their site up the rankings. However, meta tags can help influence how your website is perceived by the search engines and their crawlers, and that can help to affect their determination of your site's relevance.
Meta tags are HTML codes that can be inserted into the header of your web pages, after the meta title tag. The information meta tags carry is not seen by users who access your site, but it is used to instead transmit information about your site to browsers and, for our purposes, search engines.
The two types of meta tags you'll hear most about are meta description tags and meta keyword tags. Both of these can be used as part of your plans for search engine optimization.
Description meta tags are basically supposed to be a brief description of the focus and concern of the page in question. When someone looks up your site in a directory or accesses it through a web search, they will see your site description. In description meta tags, you should use the main keyword that your SEO marketing will focus on in the content of the page itsefl, and any other secondary keywords you are trying to plug. You should try to keep your description under 170 words, and don't make it any less concise than it has to be.
The keyword meta tags serve a similar purpose, in that they can be a good place to highlight keywords, since crawlers will find and digest them quite easily. You can list any number of keywords in these meta tags, but they work best when those keywords actually exist on the page itself.
Unfortunately, these days meta tags do not carry the importance for search engine marketing that they did a few years ago. Seeing that many people were blatantly using meta tags to as SEO tools to manipulate their rankings, many crawlers apply little or no significance to them.
However, there are still some search engine crawlers out there that do include meta tags in their algorithms to determine where to rank your site, and since they are relatively easy to include in your HTML, many web optimizers still choose to use them.
When using meta tags as part of a larger optimization strategy, they can however be helpful, as even a small boost in your desirability for a few crawlers will probably result in a bit of extra attention.