The Teletype Model 33 is an electromechanical teleprinter designed for light-duty office use. It is less rugged and cost less than earlier Teletype machines. The Teletype Corporation introduced the Model 33 as a commercial product in 1963; the machine had originally been designed for the United States Navy. There are three versions of the Model 33:

• Model 33 ASR (Automatic Send and Receive), which has a built-in eight-hole punched tape reader and tape punch;
• Model 33 KSR (Keyboard Send and Receive), which lacks the paper tape reader and punch;
• Model 33 RO (Receive Only) which has neither a keyboard nor a reader/punch.

The Model 33 was one of the first products to employ the newly-standardized ASCII code, which was first published in 1963. A companion Model 32 used the older, more established five-bit Baudot code. Because of its low price and ASCII compatibility, the Model 33 was widely used with early minicomputers, and the large numbers of the teleprinter that were sold strongly influenced several de facto standards that developed during the 1960s and 1970s.