A two-way communication channel between two users or nodes on a network, or between a user and a service.
æå·è³ç£ã«é¢ãããã©ã³ã¶ã¯ã·ã§ã³æ å ±ãæç³»åã§èšé²ããåæ£åããžã¿ã«å°åž³ã