What is the reasons for using sponsorship in marketing campaign?

Interesting question in terms of marketing. 

I have not seen much sponsorship in marketing campaign but sponsorship in sports like football, basket ball, rugby and the rest. 

Can you please name a few cases pls ? 

reason #1 is to cover up part of your campaign expenses

reason #2 if your prospective clients trust the sponser, then it will urge them to trust your product too.