Amplifiers are synonymous with music because they allow the music to be bigger than it is. Small bands in local bars as well as huge rock stars filling up arenas rely on them to get their sound out there to the crowd. You can also add one to your car sound system or your home entertainment theatre system. The sound you will get from your amplifier though will depend on the features of it.
There are many well known brands of amplifiers and you will find advertisements for them in music magazines. They are often endorsed by big stars in the music industry because the maker knows a person is more likely to be buy what their idols are using. Of course these types of amplifiers will cost more money to cover that overhead.
There are many different features of an amplifier that you need to take into consideration if you are shopping around for one. The gain is in reference to how much output you will get from the equipment. You will also need to evaluate the bandwidth that is offered for it. If the frequency is too high you may need to get a good filter to reduce the amount of vibration taking place.
Of course those overall amount of amplification that you will get from it is important too. You may only want to go up a few decibels for band practice but you will need much more when you are looking at playing at a club. You want the amplifiers that you use to be linear in nature as well. This will prevent the sounds from becoming distorted, especially at higher levels of output.
Most amplifiers that are used with musical instruments have to be plugged in. Some of the newer models don't have to be. For your home you can buy an amplifier to attach to your system. Many of the newer models of stereos for the home and the car though come with an amplifier built right into them.
You can find amplifiers at music stores for you to try out. If you play a particular instrument make sure you take it with you. Ask to try out the amplifier using that instrument so you can hear for yourself how it will amplify your sounds.