A general query.

Question

 Hello ;

 

           I want to know that websites like quickr/ OLX has big business. They have big setup and their expenses(Company Maintenance, human resource,Promotions in radio,television, free customer care support etc..) are also inconsiderable. SO What are the sources of their income. Cause only with Advertisements in their website, they can not afford these expenses.

 

              SO please, Can anyone guide me to understand  the sources of income of any websites?

 

                            Thanks in Advance.