Is it rude to say no to prom?

Would it be considered impolite or disrespectful to decline an invitation to the prom, especially if it's coming from a friend or someone you have a close relationship with? Is it necessary to offer an explanation or is a simple "no, thank you" sufficient? How might the person inviting you react to your decision, and is there a way to phrase your refusal in a way that minimizes potential hurt feelings?