With a wide selection of frames available, they can all be categorized into one of three styles: Full-rimmed, Semi-rimless, and Rimless.
Fully-rimmed frames have frame material entirely encircling the lenses. These are compatible with any prescription, and are especially beneficial for higher prescriptions.
Semi-rimless frames have frame material that only partially encircles the lenses, with the other portion generally holding the lens with a nylon wire. These are most suitable for mild to moderate prescriptions.
Only the temples and bridge exist in Rimless frames. There is no frame around the lenses at all. Keep in mind that this type of eyeglass is not recommended for higher prescriptions or single vision reading glasses that are constantly being taken on and off as the lens insertion point often puts much stress onto the lenses themselves.