Yahoo! Messenger, from its launch in June 1999, grew to 10.6 million users in August 2000, while MSN Messenger Service, from its launch in July 1999, grew to 10.3 million users in August 2000. AOL Instant Messenger, which launched in May 1997, grew from 18.1 million users in August 1999 to 21.5 million users in August 2000.
"Instant-messaging applications are proving to be very popular with consumers," said Doug McFarland, president, Media Metrix. "But their different features and lack of interoperability cause users, especially heavy users, to adopt more than one brand in order to keep in touch with all their friends and colleagues."