The cable service offered by your local company may include analog, clear digital (unencrypted), and/or encrypted digital channels. Almost every modern TV supports analog channels. To tune them in you simply plug the co-axial cable directly into your television. In order to receive clear digital channels without having to rent some sort of set top box from your Cable company, you will need a QAM tuner which can be either built into your television or in a separate device. If your TV has a QAM tuner you might be able to get local network channels in High Definition (HD) after running a channel scan on the TV with a direct co-ax connection. Look for the HD channels in the lower numbers that end in .1 like 6.1, 7.1, 13.1. These are referred to as ClearQAM channels.
Unfortunately companies like Comcast have been phasing out service of ClearQAM channels and requiring more municipalities to have a special set top box or digital transport adaptor (DTA). By encrypting all of their content they can force you to rent these DTA’s from them if you wish to watch Cable. Most cable companies are providing the first 2 free of charge for now, however if you have 3 or more televisions you can expect to pay to rent additional DTA’s.
Comcast will defend their actions by saying they are trying to prevent cable theft and improve technical support by having addressable devices in your home which will help their techs troubleshoot problems. Each device that uses a Comcast service from cable modems to DVRs must be activated with them. What they won’t offer to tell you is their new requirements force you to rent more equipment from them if you have several TVs in your home. These devices can also collect information about your viewing habits which can be sold to 3rd parties for marketing research and targeted advertising.
The main players in the Cable industry are Comcast, AT&T, Time Warner, Verizon, Cox, and Charter. Together their Cable lobby is very powerful in Washington DC. If you feel they are abusing their power you should write to your congressional representatives or the FCC.