It launched in 1995 and is now available in 24 different countries.
Members set up a profile, upload photos and can then search through profiles to find a good match.
Launched in 2004, OKCupid works with many populations of people.
Harvard Business School graduate, Mark Brooks, has been an expert in the Internet dating business since 1998.
He is currently the CEO of Courtland Brooks, a consultancy agency for the Internet dating industry, and runs Online Personals
Creating online dating profiles helps consumers carefully consider potential matches.
Likewise, evaluating a dating site before using it is essential, and it will bring you that much closer to finding a good match.
These sites have the broadest appeal and generally the largest membership bases.