The act in which people help someone without any reason, motive, or we can say personal interest is known as –

Prosocial behavior
Explanation: Prosocial behavior is a behavior that benefits society or other people and including a wide range of actions such as donating, sharing, helping, and co-operating. Obeying the rules and adaptation of socially accepted behaviors like paying for groceries or stopping at the stop sign are also regarded as Prosocial behavior.