RS-232 is a standard for serial communication introduced in 1962 that defines the electrical characteristics and timing of signals. It supports both synchronous and asynchronous transmissions of user data as a time-series of bits. Devices connected via RS-232 are classified as Data Terminal Equipment (DTE) such as computers that send and receive data or Data Communication Equipment (DCE) such as modems responsible for data transfer. The standard faces limitations including maximum transmission speed and large voltage swing, leading to the development of newer standards like USB. Various pins of the RS-232 connector including DTR, DSR, RTS, and CTS support handshaking signals to coordinate fast and reliable data transmission.