Facebook’s virtual-nudge feature was called Poke.
Poke allowed one Facebook user to send a small, deliberately ambiguous notification to another person. The recipient could poke back, creating a lightweight interaction that required no written message. Facebook offered the feature during the service’s early years, when many social-network functions were intentionally simple.
The meaning of a poke was never fixed in the way a message or status update was. Users could treat it as a greeting, a joke, or a way to attract attention. That ambiguity was part of its appeal, but it also made the feature difficult to define for people encountering it for the first time.
Poke is often confused with Facebook’s Like button or later reaction system. A Like expresses approval of posted content, while a poke was directed privately or semi-privately at another user. Facebook later removed or deemphasized Poke from much of its main interface, although the term remains associated with the platform’s early culture.