Childline, as the name suggest is helpline for children. In the cities they are present they have a toll-free telephone number 1098 (ten, nine, eight), on which any child who needs assistance can call. Calls are received by childline representatives, who are trained to take these kind of calls, and they take appropriate action, like providing medical assistance, or performing a rescue operation, or just give some emotional support.
When I was coming from Hospet, and I was waiting at the busstand. There was this, small girl about 13, and her mother (I presumed she was her mother), was forcefully taking her somewhere, and she was wailing like hell. From the clothes I could figure out that they were very poor. I did not have a nice feeling about the whole thing, but I ignored it. Probably I did not care, or I just did not have balls to interfere. Had I read about childline earlier, I would have probably given a call to 1098.
So as childline website puts it
Call 1098 when to see any child in distress
Tell every vulnerable child you see about CHILDLINE 1098