Some sites provide free registration, but may offer services which require a monthly fee.
Other sites depend on advertising for their revenue.
Members use criteria other members set, such as age range, gender and location.
Most sites allow members to upload photos or videos of themselves and browse the photos and videos of others.
Sites may offer additional services, such as webcasts, online chat, telephone chat (VOIP), and message boards.
Online dating sites use market metaphors to match people.
Match metaphors are conceptual frameworks that allow individuals to make sense of new concepts by drawing upon familiar experiences and frame-works.
Other sites are more specific, based on the type of members, interests, location, or relationship desired.