RS-232 (Recommended Standard - 232) is a telecommunications standard for binary serial communications between devices. It supplies the roadmap for the way devices speak to each other using serial ports. The devices are commonly referred to as a DTE (data terminal equipment) and DCE (data communications equipment), and could include items like a computer and modem, respectively.
Updated designations for this protocol have included EIA-232 (Electronic Industries Alliance) and the more current EIA/TIA-232 (Telecommunications Industry Association). These organizations have voluntarily taken on the protocol and the task of improving it. Though it is sponsored by organizations in the United States, the most current variety is compatible with a standard known as ITU v.24 (International Telecommunication Union). Compliance with the international standard helps manufacturers turn out products that will work in a global marketplace.
ITU is a United Nations organization and its v.24 (pronounced vee dot twenty-four) communication standards are considered recommendations. In the past, however, the slow nature of the organizations behind international standards sometimes led to varying protocols in the marketplace and the adoption of standards before they were officially "sanctioned." Today, these organizations have streamlined the process of developing and disseminating new standards.
RS-232 sets acceptable voltage and signal levels, along with common pin designations or configurations, for wiring serial connector ports. It also specifies protocols for the control information passed between devices, which includes such events such as indicating the beginning or end of a data stream.
Without standards, manufacturers would have no road map to build compatible product lines for technology. RS-232, or serial ports, are now used almost exclusively for dial-up modems. Other devices that used to use serial ports, like mice, now make use of newer USB and Firewire® ports. As the marketplace gradually switches away from dial-up modems to DSL, cable and satellite, this standard will likely eventually become obsolete.