How Many technique use In seo..?

[RHCalvin]

There are basically two types of SEO techniques - on page and off page.

On page seo refers to the process that is followed on the website itself. Some of the tasks involved are:

Keyword research
Meta tags and title
Meta description
Robots.txt file
Sitemap generation
Content development
Image optimization

Off page refers to the link building and promotion of your website in search engines. Some of the most effective off page activities are:

Guest posting
Article submission
Press release submission
Social bookmarks
Classified ads
Infographics submission
Social media optimization

[davidchao]

I want to add some others off page techniques in your list...

Directory Submission
RSS Submission
Podcast Submissition
Blog Commenting
Forum Posting

[varunroy]

There are three types of techniques in SEO.
1. Black Hat SEO - It is the technique which we use to get the high traffic and achieve ranking in search engine by going against the google guidelines.
2. White Hat SEO - It is the technique, in which we work according to Google Guidelines to achieve the ranking and high traffic from search engine.
3. Grey Hat SEO - This technique is the combination of White Hat and Black Hat SEO.