A more thorough explanation:

A three-strikes law is a legal rule that requires a person who has been convicted of a serious crime three times to receive a harsher punishment, such as a longer prison sentence or life imprisonment. This law is also known as a three-strikes-and-you're-out law.

For example, if a person has been convicted of two serious crimes, such as robbery or murder, and then commits a third crime, they may be sentenced to life in prison under a three-strikes law.

About half of the states in the United States have enacted a three-strikes law to deter repeat offenders from committing more crimes. The purpose of this law is to protect society from dangerous criminals and to ensure that they are held accountable for their actions.