The key is one of the most important parts of the track. It's impossible to make a beat without having the key in mind. Most musicians start with a simple key, such as C or E.
The beats-per-minute (BPM) determines the flow of the track. It's important to know the BPM when creating a beat so you will know the speed of your track.
The snare drum is a sound that follows after the main beat and usually has a snappy or crunch-like sound. Its presence determines the rhythm of the track and where the next beat change will go.
Probably the most crucial part of the beat is the bass or bassline. The bassline is usually played out on a synthesizer, but it can also be made with a software synth program on the computer.
Sound effects help to add dramatic effects or processing to the beat and can be added last, like a spice in food. Most sound effects are placed on drums or vocals to give them an extra flare or body.