ELI5: Explain Like I'm 5

Substance dependence

Substance dependence is when your body can't work without a certain type of medicine or drug. It's kind of like when your car needs gas to go places. The gas is like the medicine or drug and it helps your body to keep going. When your body gets used to a certain type of medicine or drug, it can’t live without it, and if it doesn’t have it, things don’t work properly. This is dependence.