Search Engine Optimization.

there are mainly two types of seo:
1. On page SEO
2. Off page SEO
On page optimization :
In on page seo, all the seo technique is done on the website. like content updation, Title tag. Alt tag and meta tag creation, Url updation, Error removal etc. this technique is mainly done by downloading the pages of a website and then uploading to the server after updation.
Learn : On page SEO ranking Factors
Off page optimization :
This technique is absolutely opposite to the on page seo. we promote thr site by putting link or data to the other site. on page SEO example is directory submission, social bookmarking,article submission, blogging etc.