This is where the cable companies make a lot of money. When my bill was over $200/month a full $120 of that was a charge for TV service. More on this later when we talk about replacing this service.
Many cable companies have a simple setup for your TV. Since the coaxial cable that goes to your cable modem also has the TV signals on it, all you have to do is connect your TV to that same cable by using a splitter. They are available at most BOX stores and even at WalMart. The cable company will probably ask you how many TV's you will be connecting and that's an old trick.
Many cable companies even charge for each TV, even though there is no optional equipment or anything special needed. I always wondered why they ask that but if you check your cable bill there will a separate charge for each TV that you admitted to. Ha! they got you again!
However, in the last 5 years there are new systems out there that require a separate little box for each TV. They figured out that if they scramble the TV signals on the cable, they can make more money by charging you for this little box for each TV. Now when they ask you how many TV's you have, it's for this reason and they will supply you a little box for each TV. At my cable company, they give you two for free and then charge you $3/month for each additional one. So yes, they got you again.