What is Forking, Cloning and Pulling in Source Code Repositories Like Github and BitBucket

This video discusses about important terminologies in source code repository such as Forking, Cloning and Pulling.
Forking is the concept of taking the source code from an open source software program and develop an entirely new program.
Cloning is the concept of getting a working copy of the remote repository.
Cloning means that getting a working copy of the remote repository.

[@gaurav_wahi]

Sorry but this is very unclear :(