Why getting the certificate of sponsorship from your employer is necessary?

The certificate of sponsorship is considered to be a very important as well as necessary document in order to get the genuine work visa in the boundaries of the U.K. 

In fact, getting the certificate of sponsorship is very important for the person if he or she is going to work there in the U.K. as it shows that the person is 100 percent genuine and can be considered to work in the U.K. for a particular employer who is appointing that particular person over there.