Chat can refer to any kind of communication over the internet, but is primarily meant to refer to direct 1-on-1 chat or text-based group chat (formally also known as synchronous conferencing), using tools such as instant messaging applications—computer programs, Internet Relay Chat, talkers and possibly MUDs, MUCKs, MUSHes and MOOes.

While many of the web's well known custodians offer online chat and messaging services for free, an increasing number of providers are beginning to show strong revenue streams from paid-for services. Again it is the Adult service providers, profiting from the advent of reliable and high-speed broadband, (notably across Eastern Europe) who are at the forefront of the paid-for online chat revolution.

For every business traveller engaging in a video call or conference call rather than braving the check-in queue, there are countless web users replacing traditional conversational means with online chat and messaging. Like Email, which has reduced the need and usage of letter, fax and memo communication, online chat is steadily replacing telephony as the means of office and home communication. The early adopters in these areas are undoubtedly teenage users of instant messaging. It might not be long before SMS text messaging usage declines as mobile handsets provide the technology for online chat.