Synchronous conferencing is the formal term used in science

Science

Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

, in particular in computer-mediated communication

Computer-mediated communication

Computer-mediated communication is defined as any communicative transaction that occurs through the use of two or more networked computers...

, collaboration

Computer-supported collaboration

Computer-supported collaboration research focuses on technology that affects groups, organizations, communities and societies, e.g., voice mail and text chat. It grew from cooperative work study of supporting people's work activities and working relationships...

 and learning, to describe online chat

Online chat

Online chat may refer to any kind of communication over the Internet, that offers an instantaneous transmission of text-based messages from sender to receiver, hence the delay for visual access to the sent message shall not hamper the flow of communications in any of the directions...

 technologies. It has arisen at a time when the term chat

Online chat

Online chat may refer to any kind of communication over the Internet, that offers an instantaneous transmission of text-based messages from sender to receiver, hence the delay for visual access to the sent message shall not hamper the flow of communications in any of the directions...

had a negative connotation. Today it is occasionally also extended to mean audio/video conferencing or instant messaging

Instant messaging

Instant Messaging is a form of real-time direct text-based chatting communication in push mode between two or more people using personal computers or other devices, along with shared clients. The user's text is conveyed over a network, such as the Internet...

 systems, given they provide a text-based

Text-based

Usually used in reference to a computer application, a text-based application is one whose primary input and output are based on text rather than graphics or sound. This does not mean that text-based applications do not have graphics or sound, just that the graphics or sound are secondary to the...

 multi-user

Multi-user

Multi-user is a term that defines an operating system or application software that allows concurrent access by multiple users of a computer. Time-sharing systems are multi-user systems. Most batch processing systems for mainframe computers may also be considered "multi-user", to avoid leaving the...

 chat function. The word synchronous in this case is not to be considered a technical term, but rather describing how it is perceived by humans—chat happens in real time before your eyes.

Synchronous conferencing protocols include:

• IRC
  Internet Relay Chat
  Internet Relay Chat is a protocol for real-time Internet text messaging or synchronous conferencing. It is mainly designed for group communication in discussion forums, called channels, but also allows one-to-one communication via private message as well as chat and data transfer, including file...
  
   (Internet Relay Chat)
• PSYC (Protocol for Synchronous Conferencing)
• SILC
  SILC (protocol)
  SILC is a protocol that provides secure synchronous conferencing services over the Internet.- Components :...
  
   (Secure Internet Live Conferencing protocol)
• XMPP
  Extensible Messaging and Presence Protocol
  Extensible Messaging and Presence Protocol is an open-standard communications protocol for message-oriented middleware based on XML . The protocol was originally named Jabber, and was developed by the Jabber open-source community in 1999 for near-real-time, extensible instant messaging , presence...
  
  (Extensible Messaging and Presence Protocol)