Child sexual exploitation remains "woefully under-reported" in the UK, the NSPCC has warned.
The charity said many young victims do not understand they are being groomed and exploited because of the tactics offenders use. It called on adults with concerns to raise the alarm.
Efforts to tackle abuse have come under the spotlight in recent years following scandals in Rochdale, Rotherham and Oxford.
The NSPCC disclosed that nearly 2,000 of the country's most vulnerable youngsters have been helped by the Protect and Respect service it set up in 2011.
NSPCC Chief Executive Peter Wanless said: "Young people will not always recognise that they are being exploited and treated as property.
"We want every child to be able to spot exploitation for what it is and, if they find themselves in danger, know that it is categorically not their fault.
"Our Protect and Respect service is showing them how to spot potential abusers, find their way out of an exploitative cycle and help them on the road to recovery.
"We are imploring any adult who suspects a child is being exploited to pick up the phone and call the NSPCC Helpline.
"This abuse is sadly still woefully under-reported and, for us to help these children, we need people to speak up."
Launched in November 2011, Protect and Respect is open to 10 to 19-year-olds and works with agencies such as the police and social services to identify and support youngsters who have been sexually exploited or are at risk of falling victim.
The service has directly helped 1,866 children and young people, including 1,493 aged from 10 to 15.
Earlier this year, ministers unveiled plans for a new £40 million blitz on child sexual exploitation.
The drive includes the launch of a new centre of expertise and plans to create a new national database of missing people.
Calls for authorities to step up their response to the issue intensified in the wake of a flurry of high-profile episodes.
In 2014, a major report detailed how at least 1,400 children were sexually exploited in Rotherham over a 16-year-period, sparking nationwide outrage.
The warning from the NSPCC comes ahead of the start of Three Girls, a new BBC drama based on grooming and sexual abuse cases in Rochdale.