Purpose of Modulator for a CATV Ampifier

I am going to install an amplifier to connect 8 TV in my home. The amplifier has a Cable-IN post, A DC12V Cable Pwr Post, and a MOD 1 IN Post. It is the latter post I am concerned about. Do I need an amplifier? Would it improve the signal significantly? If, I need to use an Modulator what would you suggest I look for. Please make your answer simple. I know a lot of things but none of them fall in the electronic arena! Jim