Most defendants now appear in this kind of court. There is no jury of ordinary people, the magistrates (or judges) make the decisions.
The defendant has to say if they are 'guilty' or 'not guilty'.
If the defendant says that they are guilty then the magistrates make their decision over what the punishment will be. This is also called 'sentencing'.
If the defendant says they are not guilty then the Crown Prosecution Service tells the court why they think they are guilty.
For the most serious crimes, like murder, the defendant has to go to the Crown Court.