Your laptop computer has a number of ports on it--on one or both sides and sometimes even the back or the front--designed to interface with a variety of different types of hardware or connectors. If you'd like to know whether a given port is for connecting to a printer, a FireWire cable or a remote monitor, you must locate the symbols associated with each port and determine what sort of connection they represent.
Check around the port for a symbol. In the case of older laptops with serial ports, this may be a clear depiction of the type of hardware you connect with through that port (for example, a tiny picture of a printer, monitor or mouse).
Match the symbol on the laptop port to the symbol guides in the "Resources" section, below. Each guide lists not just the name of the port designated by each symbol, but also what each port is used for.
Compare the shape of the port to the views of ports and connectors given in the "Resources" section. If there is no symbol given, this is the only way to identify the various ports and their purposes.