There are Several Meta tags are:
1. Description Meta Tag
2. Generator Meta Tag
3. Keywords Meta Tag
4. Revisit-After Meta Tag
5. Robots Meta Tag
6. Content-Type Meta Tag
7. No-Cache Meta Tag
8. Audience Meta Tag
9. Author Meta Tag
10. Content-Language Meta Tag
11. Page-Topic Meta Tag
12. Page-Type Meta Tag
13. Prog Id Meta Tag
14. Publisher Meta Tag

1.Title
2.Description
3.Keyword
4.Robots
These are the main types of meta tag.

Mainly you can focus on Meta title, Meta keywords, Meta Description.

Meta tags are:
- Meta Title
- Meta Description
- Meta Keywords
- Robots Tag
- Alt Tag

Meta Title
Meta Description
Meta Keyword

Meta Title,
Meta keyword,
Meta Description.

How many types of Meta Tag ?
 

Title Tag
Description Tag
Keyword Tag

Type of meta tag are :-
Content-Type Meta Tag
No-Cache Meta Tag
Audience Meta Tag
Author Meta Tag
Content-Language Meta Tag
Description Meta Tag
Generator Meta Tag
Keywords Meta Tag
Page-Topic Meta Tag
Page-Type Meta Tag
ProgID Meta Tag
Publisher Meta Tag
Revisit-After Meta Tag
Robots Meta Tag

Types Of Meta Tags...
1. Description Meta Tag
2. Generator Meta Tag
3. Keywords Meta Tag
4. Revisit-After Meta Tag
5. Robots Meta Tag
6. Content-Type Meta Tag

Meta Tag Types
Tittle tag
description tag
keyword tag
Robots tag

Keyword MetaTag
Title Meta Tag
Description Meta Tag
Robots Meta Tag

Meta Title tag
Meta Description tag
Meta keyword tag
Meta Robots tag

Meta tags are important for website see the types of meat tags are in the following page title,description,keywords,abstract,author,robot tag.

Three types:
Meta title
Meta description
Meta keywords