The numbers show a sharp increase from 55 incidents of crimes that mentioned Tinder or Grindr in 2013, to 412 in the year to October 2015.Among the reported crimes were cases including rape, grooming, and attempted murder.

The 2016 Pew Research Center's survey reveals that the usage of online dating sites by American adults increased from 9% in 2013, to 12% in 2015.

Further, during this period, the usage among 18- to 24-year-olds tripled, while that among 55- to 65-year-olds doubled.

Online dating (or Internet dating) is a system that enables strangers to find and introduce themselves to new personal connections over the Internet, usually with the goal of developing personal, romantic, or sexual relationships.

An online dating service is a company that provides specific mechanisms (generally websites or applications) for online dating through the use of Internet-connected personal computers or mobile devices.

Other sites target highly specific demographics based on features like shared interests, location, religion, or relationship type.

Online dating services also differ widely in their revenue streams.

Grindr appeared on 135 crime reports last year, up from 34 in 2013.

Both dating platforms downplayed the figures in comparison to their overall user numbers, but urged users take steps to protect themselves, reports the BBC.

That is, online dating sites use the conceptual framework of a "marketplace metaphor" to help people find potential matches, with layouts and functionalities that make it easy to quickly browse and select profiles in a manner similar to how one might browse an online store.

Under this metaphor, members of a given service can both "shop" for potential relationship partners and "sell" themselves in hopes of finding a successful match.

Some sites are completely free and depend on advertising for revenue.