>>12812854Observing hoe certain quantities are related to one another.
Maybe you're working with springs and want to find out the physics behind them.
It's intuitive to find that the further you stretch the spring, the more force it takes. So you experiment on multiple springs and plot the force required as a function of distance. You should hopefully find that all the lines have the same slope, and that F = k*x, where k is the Spring constant.
Tldr: numbers are proportional to other numbers
