Others utilize the freemium revenue model, offering free registration and use, with optional, paid, premium services.
Still others rely solely on paid membership subscriptions.
Online dating services also differ widely in their revenue streams.
Some sites are completely free and depend on advertising for revenue.
Further, during this period, the usage among 18- to 24-year-olds tripled, while that among 55- to 65-year-olds doubled.