A more thorough explanation:

Definition: Standing to sue means a party's right to make a legal claim or seek judicial enforcement of a duty or right. In order to have standing in federal court, a plaintiff must show that the challenged conduct has caused them actual injury and that the interest sought to be protected is within the zone of interests meant to be regulated by the statutory or constitutional guarantee in question.

Example: Let's say a person is injured in a car accident and wants to sue the other driver for damages. They have standing to sue because they have suffered actual injury and their interest in seeking compensation for their damages is within the zone of interests meant to be protected by the law.

Third-Party Standing: Third-party standing is held by someone claiming to protect the rights of others. For example, in most jurisdictions, only a parent has standing to bring a suit for custody or visitation. However, in some cases, a third party, such as a grandparent or a person with whom the child has substantial contacts, may have standing to bring an action for custody or visitation.

Example: If a grandparent wants to sue for visitation rights with their grandchild, they may have standing to do so if they can show that their interest in seeking visitation is within the zone of interests meant to be protected by the law and that they have a substantial relationship with the child.

Overall, standing to sue is an important concept in the legal system that ensures that only those who have suffered actual injury and have a legitimate interest in seeking judicial relief can bring a lawsuit.