The most basic receiver that you will be able to obtain is a tuner receiver. No bells and whistles will come with this one. The key benefit of this receiver is not buttons and dials on the front of the receiver, but the plugs on the back. Most of these receivers will have multiple plugs and inserts on the back that can be used to plug in your CD player, DVD player, Tape Deck, or any other audio device that you may be able to plug. The Aux input can even be used to plug in your 8-track, if that 8-track can be rigged to use RCA cords.
The other most popular receiver is a multi-disc changer. Most of the time, these receivers will have a 5-disc changer that is able to play DVDs, CDs., and MP3 discs. This one unit is able to fulfill all of your audio and visual needs for your surround sound home theater systems.
There are two major functions on your receiver that you need to understand when buying a home theater system. The first is wattage. Most of your receivers will have an amp already inside of them, and you need to know how much power it allows them to put out. If your speakers are able to handle more power than your receiver, you wasted some money on your speakers. The other function is the number of inputs in your receiver. Most will have 2 or 3 inputs for additional sound equipment. Other more extravagant home theater systems will have 7 or 8 different inputs.