What is the difference between Lync and Sharepoint?

Both seem to serve the same purpose,then why do they both exist? and another question is,is the sharepoint hosted by onedrive or its an independent platform?i got really confused with all these similar services in microsoft. Even skype does similar tasks like Lync does.all these things really making little complected.can anyone please care to explain clearly?I really love to use Lync for working with my colleagues,but before that i want to make sure that i know enough about other services also.