Asking for too much sensitive information is one of the signs of a scam. Some unscrupulous people take advantage of their victim's hopes of winning contests to lure them into providing information that can be used for identity theft. And yet, even legitimate contests ask for so much personal information that it can be difficult to tell what's reasonable and what's not. Here are some types of information that you might see on contest entry forms, and whether it is safe to provide this information or not.
Identification and Contact InformationIn order to contact winners and uncover duplicate entries, many contest entry forms ask for contact information like your full name, address, telephone number, and email address. Note that this information is generally a matter of public record in any case. This is totally standard for contest entry forms, and nothing to worry about.
See What Information Should I Use on Sweepstakes Entry Forms? for more details.