MAX232 RS-232 Level Shifter IC

Level shifters are able to convert a low voltage to a high voltage.

MAX232 is a level shifter which translates voltages so that your micrcontroller can talk to your PC through an RS-232 port. This translates between the 0 to 5V TTL level voltages to the +/-12V levels required by RS-232. These ICs come in  DIP package making them suitable for breadboard prototyping. 

Documents

• Maxim MAX232 Datasheet
• Tutorial about RS-232 and translation by Sparkfun Electronics