Even though the basic purpose of a guitar amp doesn't change, people buy them for different reasons. Vintage enthusiasts buy them to add to their collections. Beginners buy new and used amps to get good sound from their guitars at a reasonable price. Professionals buy them to fill arenas with thundering, hard-rock sonic blasts. While most electric guitar amps are merely intended to reproduce sound clearly, some amps are intended to produce distortion for artistic effect (mainly those used for arena-style rock produced by electric guitars. Acoustic guitar amps may be used with acoustic/electric combos that have built-in pickups.

Here are some of the basic elements to look at when evaluating guitar amps. Combo amps combine the amplifier and loudspeaker into a single unit. Stack amps separate the speaker and amplifier into separate units (usually stacked on top of one another). Unless you plan to play a large venue, a combo amp will usually suffice.

Solid state amps are traditionally cheaper, while vacuum tube amps are considered the amps of choice for serious players. Modern digital amps can simulate the sound of vintage guitar amps at an affordable price. Although not as common as traditional amps, these so-called 'modeling' amps can give even a beginning guitarist access to a lot of sound.

As far as loudness goes, more watts typically produce louder sound. This isn't always the case, but a 30 watt amplifier will not produce anything like the volume of a 100 watt amp. For public performances, a guitar amp should generally be rated at 50 watts or higher. Prices on guitar amps can range from around a hundred bucks to thousands of dollars.