WHAT IS HOME THEATER
The term home theater is a very relative term. The smallest level of home theater consists of a hi-fi VCR, and a stereo TV. All that is needed is wiring to run from place to place in order to connect everything.
However, when someone mentions the words "home theater", it is understood that there is at least a 27" TV, a Dolby Pro-Logic receiver, and a Hi-Fi VCR. The bare bones for the speaker set-up is a four speaker set-up: Left and Right for the front, a Center speaker, and a Surround Speaker. More commonly you will find two surround speakers as well as an independent sub-woofer, as well as Laserdisc player. With all of these combined, you will be in a pretty good home theater set-up.
The highest level can reach a price range upwards of $50000. These usually consist of Data-grade or Graphics-Grade Front Projectors . These are usually couple with line-doublers or triplers or quadruplers, as well as a high-precision screen. The speakers that are chosen for these theaters are very often THX certified. There are usually at least 2 powered sub-woofers, and now, many of them are converting to the Dolby Digital (AC-3) format. The speakers are powered by a separate processor and amplifiers for each speaker, rather than a receiver handling all of the speakers. As for the room itself, it is usally decorated with curtains, plush seats, as well as a system center that has EVERYTHING in one spot, including lighting. Some people go even as far as to have a "lobby" outside their theater. Anyone who achieves this level of home theater is DEFINITELY a fanatic.
The whole purpose of home theater is to have a nice big picture, as well as deep-bass handling sound and surround sound. A very good home theater set-up will rival or even beat out the local movie theater in terms of quality.
These information are taken from General Home Theater Info/Advice