Link Building tasks are:
Micro Blogging
Guest posting
Forum posting
QnA
Blog commenting
Article Submission
Local Listings
Quality Content
Video sharing
Social Bookmarking
Infographics
PPT/PDF
There are many tasks in Link Building like:
Blog commenting
Article Submission
Local Listings
Quality Content
Video sharing
Social Bookmarking
Infographics
PPT/PDF
Micro Blogging
Guest posting
Forum posting
QnA