It's common practice for new technology companies, whether developing a new social network or a mobile app, to offer a limited number of "beta" invites before providing access to the general public. This does more than supply the company with a test environment for their product; it creates a buzz due to the exclusive nature of these invitations. Pinterest, which recently skyrocketed in popularity to become one of the hottest social networks, started out by requiring users to sign up for a waitlist to join. Similarly, in the early days of Gmail, now probably the most popular web-based email client, you had to be invited to set up an account by someone who already had one. Another example is the music streaming service Spotify which recently took the US by storm, initially launching in this country with a limited number of account invitations. You can even trace Facebook's unprecedented success back to its days as an exclusive, college-only social network requiring a ".edu" email address to join, a differentiating factor that helped propel it past existing competitors like MySpace and Friendster.