Components are seperate speakers. You might buy a set that has 2 6.5" and 2 4" and 2 tweeters and 2 crossovers. Some speakers come with two or three individual speakers mounted to each other and put in one location per side. They are known as 2-way or 3-way. Components are usally better speakers with more mounting options as opposed to the 2 or 3 ways. The mid bass thing comes from speakers ranging from 5.5 to 7 inches. Good midbass is important if you want a good sounding system. A lot of the drums, bass guitar and vocals are heard through these. Usually the bigger the speaker, the more bass it will produce. A subwoofer is for low bass, a tweeter is for high pitched sounds and the mid bass falls in between them.