All criminal statutes define crimes in terms of required acts and a required state of mind, usually described as the actor's "intent". These requirements are known as the "elements" of the offense. A prosecutor must convince a judge or jury that the person charged with the crime (the defendant) did the acts and had the intent described in the law. For example, commercial burglary is commonly defined as entering a structure (such as a store) belonging to another person, with the intent to commit petty or grand theft (that is, to steal) or any felony. To convict a person of this offense, the prosecutor would have to prove three elements:

1. The defendant entered the structure.

2. The structure belonged to another person.

3. At the time the defendant entered the structure, he intended to commit petty or grand theft or any felony.

Example: Steve was stopped by a security guard as he left a department store. His oversized backpack contained three pairs of expensive running shoes and nothing else. After interviewing the guard, who described seeing Steve take the shoes and leave without paying for them, the prosecuting attorney decided to charge Steve with burglary.

At the trial, the prosecutor was able to prove the following three elements:

1. Steve entered a structure listed in the burglary statute. (The state statute included the term "store.")

2. The structure belonged to another person. It was easy to show that Steve did not own the store.

3. Steve entered with the intent to commit theft. The prosecutor convinced the jury that Steve's use of an oversized, empty backpack was evidence that, at the time he entered the store, he was planning to stash stolen goods. The jury didn't buy Steve's claim that he only decided to steal the shoes (and therefore formed the intent to steal) after he had entered the store.