For those beginning guitar, trying to understand the specifications of guitar amplifiers is a real challenge. There are some facts that are important to know, and there are some that won't matter now, but will enrich your experience along the way. For the aspiring guitarist, here's a basic, elementary education regarding amplifiers.

Tubes
This is a type of amp that uses vacuum tubes for their pre-amp and power sections. Tube amps have a distinct tonality which is fat and rich. The distortion associated with these amps is generally accepted as outstanding and the standard for how electric guitars should sound. Almost all guitar amps that are considered 'legendary' in history are tube amps, including famous and sought after models such as Soldanos, Fender Reverbs, Marshall Plexis and JCM series. Tube amps are more powerful than solid-state amps of the same wattage. The vast majority of tube amps include distinct channels so the user can switch from clean to distorted as needed.

Solid-state
Guitar amplifiers that come under the solid state category make use of transistors instead of tubes, and were seen as the next step in amplifier evolution when first released. Indeed, it was thought they'd eventually make tube amps redundant. However, although solid state amps have a fairly large market share, the top end is still dominated by tube amps. Solid State amps are very reliable and often have a very clean tone, but also with distortion options built in. These amps are exemplary as amps for players just starting out.

Modeling Amps
These amps are a fairly recent innovation, using advances in audio science to model and then replicate the sound of classic valve amplifiers. The software used by these amps replicates the way tube amps process audio, and so can mirror the distinct sound of certain amplifiers and cabinets. Guitarists who consider themselves purists generally still choose tube amps, but modeling amps are very popular as they offer a huge range of sonic choice for an achievable price. Line 6 is one of the main companies involved in amp modeling and they have a huge range of amps, effect units and stomp-boxes which offer a close replication of expensive, vintage gear.

Hybrids
These amplifiers are an attempt to assimilate the best of tube and solid state science into one package. These amps utilize a tube in the preamp section in combination with the solid state power compartment of their amps. Marshall Valvestate amps are an example of this technology.