A more thorough explanation:

Definition: Third-party standing refers to the right of someone to bring a legal claim on behalf of another person or group.

In order to have third-party standing, the person bringing the claim must show that they have a personal stake in the outcome of the case and that the interests they are seeking to protect are within the scope of the law or constitution.

For example, a grandparent may have third-party standing to bring a custody or visitation case on behalf of their grandchild in some jurisdictions. This means that the grandparent can bring the case even though they are not the child's parent, because they have a personal stake in the outcome and are seeking to protect the child's interests.

Another example of third-party standing is when an advocacy group brings a lawsuit on behalf of a larger group of people who are affected by a particular issue. For instance, a disability rights group may bring a lawsuit on behalf of people with disabilities who are being denied access to public transportation.

Overall, third-party standing allows individuals or groups to bring legal claims on behalf of others who may not be able to do so themselves, in order to protect their rights and interests.