Solid Body Guitars

Most electric guitars are solid body guitars like the Les Paul, SG, Stratacaster and telecaster.

Acoustic and Hollowbody Guitars

Guitar that are hollow in the middle are mostly Acoustic guitars.
There are a few electrics that are also hollow in the middle, these are normally Jazz guitars and are called archtops. There is one electric guitar that is a Semi-Hollowbody, the neck goes all the way through the body so the pickups are mounted on solid wood. But from the pickup to the side it is hollow.

Other Types of Guitars

A Dobro has a metal resonator in the middle and gives a unique tone, this is a great slide guitar and the necks come either square for laying flat playing or rounded for playing like a normal guitar.

The B.B. King model is a semi-hollowbody without the F-holes on the top.

Guitar can come with two necks attached to one body. These are usually 12-string / 6-string models or 4-string / 6-string models.

Bass Guitars

Bass Guitars are four string guitars that play an octave lower than a normal guitar. There are also 5, 6 and 7-string models no available. Some basses do not have frets and are known as fretless bass guitars.

A acoustic bass can be played without an amp like an acoustic  guitar.