A criminal case is when the local, state or federal government brings an action (lawsuit) in court against a person for alleged violation of a law. The person being charged is called the defendant. The government is represented by a prosecutor.
Defendants have many more rights than do plaintiffs in civil cases, including the right to remain silent at all stages of the case and to be represented by an attorney, free of charge for people who cannot afford to hire one. Read more about what happens at each stage of a criminal case, from arraignment to trial.
The prosecutor must prove that the defendant committed the crime beyond a reasonable doubt at the trial, which is done by calling witnesses and presenting other evidence. After the trial, a judge decides whether or not the defendant is guilty.
Before a trial starts the defendant is arraigned in a courtroom by a judge. They will be asked to enter a plea or have a pre-trial conference to discuss possible resolutions. The defendant will also have limited pretrial discovery, but with special restrictions to protect the identity of witnesses and prevent intimidation.
During the trial, both sides will present their arguments to the jury. The jury will then deliberate and decide if the defendant is guilty or not guilty. If a guilty verdict is returned, the judge will set a sentencing date. If a not-guilty verdict is returned, the defendant will be released. They will not be re-tried, because the Constitution prohibits double jeopardy.