Most services also encourage members to add photos or videos to their profile.
Once a profile has been created, members can view the profiles of other members of the service, using the visible profile information to decide whether or not to initiate contact.
Some sites are completely free and depend on advertising for revenue.
Others utilize the freemium revenue model, offering free registration and use, with optional, paid, premium services.
Some have a broad membership base of diverse users looking for many different types of relationships.
Most free dating websites depend on advertising revenue, using tools such as Google Ad Sense and affiliate marketing.
Since advertising revenues are modest compared to membership fees, this model requires a large number of page views to achieve profitability.
However, Sam Yagan describes dating sites as ideal advertising platforms because of the wealth of demographic data made available by users.
There are mixed opinions regarding the safety of online dating.
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.