What do Amplifiers do?
Amplifiers, or amps, are aptly named because they amplify an electric current through a speaker.
So you’re taking the small amount of sound produced by an electric guitar, for example, and boosting it electronically. This works because amps have an external power source they can draw from to boost the current produced by the guitar.
Check out the maths behind amplification here.
Amplifiers are designed to work better with some frequencies, or pitch ranges, than others, so it’s important to match the register of the instrument you’re using with the correct type of amplifier.
The wattage on an amplifier indicates how much power the amp will use. This correlates to the loudest volume possible on the amp. Bass amps generally have the highest wattage.