Such sites earn revenue from a mix of advertising and sale of additional options.

Profiles created by real humans also have the potential to be problematic.

For example, online dating sites may expose more female members in particular to stalking, fraud, and sexual violence by online predators.

While some sites conduct background checks on members, many do not, resulting in some uncertainty around members' identities.

For instance, some profiles may not represent real humans but rather "bait profiles" placed online by site owners to attract new paying members, or "spam profiles" created by advertisers to market services and products.

At the end of November 2004, there were 844 lifestyle and dating sites, a 38% increase since the start of the year, according to Hitwise Inc.

The stigma associated with online dating dropped over the years and people view online dating more positively.

Introduction sites differ from the traditional online dating model, and attracted a large number of users and significant investor interest.

In Eastern Europe, popular sites offer full access to messaging and profiles, but provide additional services for pay, such as prioritizing profile position, removing advertisements, and giving paying users access to a more advanced search engine.

Over 50% of research participants in a 2011 study did not view online dating as a dangerous activity, whereas 43% thought that online dating involved risk.