On page and off page seo activites

On Page SEO refers to the activities that canbe done on the website.

Page Title (Meta Title) contains keywords
Meta Tags
Meta Description 
Header Tags with Keywords(H1, H2, H3, H4 etc.)
URL Structure with keywords
Keyword Density around 2.5 %
Internal Linking

External Link

Image in the Page
Image ALT Tag
Bold and Italic important lines with keywords

Minimum of 300 Words

Off page SEO refers to all the activities that is done out side or off the website.

Article Submission
Blog Commenting
Forum Posting
Directory Submission
Social bookmarking
Press Release
Social Networking Sites
Search Engine Submission
Link Baiting 
Photo Sharing 
Video Marketing
Content Marketing(Submission) etc..