Some of these niche sites are Farmersonly.com, Millionaire Match.com, Geek2Geek.com, JDate, Dandy, Pinksofa.com, Christian Mingle and Positive Singles.
Depending on the dating site, all other members might be able to see your profile and message you.
It works with special algorithms that match users with potential dates.
Launched in 2004, OKCupid works with many populations of people. It uses a compatibility matching system to link up people with complementary personalities and lifestyles and has worked with millions of users over the past 15 years.
Around 49 million singles have tried online dating at some point in their lives.