Dui
In short
Driving under the influence is the crime of operating a vehicle while impaired by alcohol or drugs. This impairment makes it unsafe to control the vehicle properly.
In plain words
It means driving when you are drunk or high. This includes using illegal drugs or even certain prescription medicines that make you sleepy or confused.
A simple example
A person drinks several pints of lager at a pub and then gets behind the wheel of their car. Because the alcohol slows their reactions, they are committing a DUI.
Why it matters
It is a major cause of road accidents and deaths. Laws against it exist to protect drivers, passengers, and pedestrians from impaired motorists.
Easy to mix up
It is often confused with DWI, which stands for driving while intoxicated, though the legal definitions vary by region.