Over the past few years, instant messaging (IM) has become a vital form of electronic communication. Today, it is significantly transforming how--and how well and how quickly--people worldwide can communicate. This article reviews three IM service systems--AOL's AIM Pro 1.4, Microsoft Windows Live Messenger, and Yahoo Messenger 8.1. In doing so, it identifies the three major issues involved in using IM. It then discusses each IM system's capabilities and shortcomings.