A more thorough explanation:

A durational-residency requirement is a rule that requires a person to be a resident of a particular state for a specific period before they can exercise a particular right or privilege. For example, some states require that a person must live in the state for at least one year before they can receive in-state tuition rates at a public university.

However, when this requirement is applied to voting, it has been found to be unconstitutional. This is because it places an unfair burden on a person's right to vote and their fundamental right to travel.

For instance, if a state requires that a person must live in the state for two years before they can vote in a state election, this would be considered unconstitutional. This is because it would prevent people who have recently moved to the state from being able to vote, even though they may have a legitimate interest in the outcome of the election.

Overall, durational-residency requirements can be used to restrict certain rights and privileges, but they must be carefully evaluated to ensure that they do not violate a person's constitutional rights.