Control characters - ASCII codes which are used for special functions, not in the text of the data (See the control character list page for details)
DCE - Data Communication Equipment (for example a modem)
DTE - Data Terminal Equipment (for example a computer)
Handshaking - Controlling the flow of data, allowing the receiving machine to stop the data flow by using control lines or characters
Hardware handshaking - The use of additional wires to control the data flow
Software handshaking - The use of additional characters to control the flow of data. (See XON/XOFF in the notes page for more details)
XON/XOFF - Software handshaking flow control by sending control characters between the machines with the data