Most people associate the concept of percussion with drums, sometimes even using the terms interchangeably. There is good reason for this, as drums are the most commonly used and arguably the most important percussive instruments. Drums are percussive instruments which are built by stretching a material—historically it was often the skin of a goat, cow or antelope, but today it is more likely to be a synthetic material—over the opening in a vessel. The sound reverberates from striking the surface, which is called the drum head.
Drums are most commonly used to maintain the beat, or accentuate a rhythm. Drums can range from bongos, to a snare drum, to a full drum set. Each of these make distinct sounds and is played in its own way—though always by striking the drum head with either fingertips, drum sticks or drum brushes.
However, percussion also describes any type of musical instrument that produces sounds through means of striking, scraping or plucking the instrument in order to develop and maintain rhythm. Therefore, plucking the strings of something like a harp to create rhythmic vibrations would also qualify as part of the percussion repertoire.
To master a full drum set requires a lot of practice and skill. Often beginners start by just trying to keep the beat on the bass drum with their feet, and develop from there. There are many different kinds of drum sets available, but all of them, when used at a high level, allow you to play multiple kinds of drums at the same time.
All of these instruments have in common the purpose of keeping time with the music, as well as adding to the total sound and effect of a song. Most drum sets will have at minimum a bass drum, a snare drum, and toms. Cymbals are also frequently a part of drum sets. From there, the sets become more complicated. Double-bass drums are one add-on option, as are multiple kinds of cymbals and snares. It might be best to start with something easy and affordable as you figure out what your style and tastes are as a musician.
With all drums, you will get a much better sound if you take care of your instrument. Just as you would tune your guitar, you need to make sure your drum set is in the best condition to create the optimal sound. This means replacing the drum heads every so often, as they will understandably get worn down. Sometimes it will also mean tightening the snare or cymbal to create a distinctive sound.
There are a wide variety of percussion drums available. Which one is best for you and/or your band will depend on what you are trying to accomplish, as well as you budget. If you are looking to just get some practice, you might not need more than a stand-alone snare drum on which you can perfect your technique. And then you can develop your drumming skills and determine what you need from there.