A drum machine is a tool used to create and play drum sounds.
Drum machines can be hardware devices, software instruments, apps, or built-in tools inside a DAW.

Drum machines allow producers to:
Many drum machines use pads.
Each pad can trigger a different sound, such as a kick, snare, clap, hi-hat, cymbal, or percussion sound.
Some drum machines use a step sequencer.
A step sequencer lets the producer place sounds on a grid. Each square or step represents a point in time. When the pattern plays, the drum machine plays the selected sounds in order.
Step sequencing is useful because it helps producers see the rhythm visually. You can place a kick on certain steps, add a snare on others, and build hi-hat patterns across the grid.
Drum machines also allow producers to adjust velocity. Velocity controls how hard or soft a drum sound plays. Changing velocity can make a beat feel more human and less robotic.
Another important feature is swing. Swing slightly shifts the timing of certain notes. This can make the rhythm feel more relaxed, natural, or groovy.
Drum machines may also include sound shaping tools. These can include tuning, pitch, decay, filters, distortion, reverb, and compression.
A producer can use a drum machine to create a simple loop, then build that loop into a full beat by adding variation, fills, drops, and transitions.
The key to using a drum machine well is listening. Do not only look at the pattern. Listen to how the drums feel together.
Akai MPC
Native Instruments Maschine