ICQ

ICQ brought instant messaging to early internet users with numbered identities, the famous alert sound, and a sense of global novelty.

A number could become an online identity. Finding friends, checking who was available, and waiting for the message alert turned a background desktop program into a connection with people beyond the room. The service made presence itself useful information.

ICQ's unusually long lifespan also means its name carries memories from different periods. The early desktop experience, with its distinctive alerts and numbered contacts, is only one phase of the service, but it remains a clear example of how small interface details can become part of personal history.

Modern messengers surpassed its old network and user base.