Creatine is a body's own substance and is mainly found in meat. Meat contains approx 5 grams creatine per kilo. Because you are most likely not going to eat one kilogram of meat every day, you can supplement the shortage with the supplement: creatine monohydrate.
How does creatine work for you?
Creatine can be compared to a cylinder of a car. The greater the volume of the cylinder, the more energy the engine can deliver. By increasing the cylinder capacity, you increase volume, which increases the car's power.
Creatine therefore provides an extra energy supply to the muscles during the first 10 seconds of a set [1]. This means you get tired less quickly and you can do more repetitions. (On average 5-10 percent strength increase with the main lifts [1]) By increasing the energy supply in the muscles you increase the risk of supercompensation.
It is recommended to take 0.04 grams per kilo of body weight. This is for someone 80 kilograms about 3 grams per day [1].
Creatine loading phase
You can omit a loading phase of 20 grams per day for one week. There is no research that confirms that this is better. This way you can use your pot for longer. 
What are the side effects?
If you do not experience any health problems with your stomach and/or intestinal tract, creatine will not do any harm. In addition, your body retains more fluid, which can cause you to gain 0.5 to 1 kg. This fluid is stored in the muscle, giving you a better pump after training. So don't worry about this.
Sources
[1] M. Hall and TH Trojian, “Creatine supplementation,” Curr Sports Med Rep, full. 12, no. 4, pp. 240–244, Jul. 2013, doi: 10.1249/JSR.0B013E31829CDFF2.
EN 
NL 