Years ago, the main search engines (which back then were Lycos, AltaVista and Yahoo and a few more) used meta tags to decide which results were the most relevant.
By the time Google became popular, they were becoming less and less relevant.
Meta tags consist of a title, description and keywords.
The Title tag and description appear in the search results:
The title should be about 60 characters long and the description no more than 160 as Google will cut off the rest (ouch).
These are no longer valued by Google or Bing as ways to prioritise your website over someone else's. Metatags are not visible when you visit a site.
So think of them more as an advert in the SERPs. A catchy title and description might be the difference between clicking and not clicking on your website.
If you’ve not defined a description Google will use the first few lines of your website as the description. So if you’re relying on this, some of the text may look odd or truncated.
The Keyword meta tag
These went obsolete ages ago and are no longer used by any search engine to value the quality of your website. This is mainly because people just added tonnes of words and abused the Keyword tag.
The best way to get your site up Google and Bing, is to write for humans who like good quality content that makes them want to buy from you!