How many types of meta tags are used in SEO?

[jeet1]

How many types of meta tags are uses in seo?

[guinanie]

META tags can still influence a search engine when it comes to deciding whether your web page is relevant or not.

Keywords META tag:
15-20 keywords, include misspellings of keywords/keyphrases
Description META tag:
Include keywords/keyphrases, 25-30 words, no more than two sentences.

[Elquicos]

I personally only care about title and meta description

[Datasolutioninc]

Meta tag use in Title and description.

[peterko]

META tags can still influence a search engine when it comes to deciding whether your web page is relevant or not.

Keywords META tag:
15-20 keywords, include misspellings of keywords/keyphrases
Description META tag:
Include keywords/keyphrases, 25-30 words, no more than two sentences.

As you probably know, keywords meta is no longer taken into consideration by the major search engines due to keywords abuse by webmasters. You can still use them in your code but it doesn't have so much value.

What is the most important, the <title> and <description> meta tags, because they are listed in the SERP when users type search criteria.
Also try not to abuse those meta tags, they should not be too big and of course they have to be user friendly.

Have a great day,
Peter

[aira]

title and description are the most commonly used tags though it's not necessary to use them always

[josh08]

yup! meta tags are keywords and description