Gateway drug theory

Gateway drug theory is a theory that suggests that using certain drugs can lead to using harder, more dangerous drugs later on. For example, it's thought that using marijuana (a drug that isn't as bad for you as other drugs) can lead to using harder drugs like cocaine or heroin (drugs that can be very dangerous). It's like when you go from one step to another on a staircase - the first step isn't as high as the last one, so it's easier to climb the staircase and get higher and higher as you go along. The same idea applies to drug use - it's easier to use more dangerous drugs and get hooked if you have already started using less dangerous drugs.