In audio acoustics a port refers to an opening in a bass reflex-type loudspeaker enclosure. Ports are usually tuned very carefully to create certain kinds of resonances and coupling with the air outside the cabinet. They come in many shapes, sizes, and are even found in different locations on speaker cabinets. The purpose is to improve the bass response characteristics of the enclosure, which is often accomplished specifically by creating a controlled resonance of the air at a frequency just below the normal cutoff frequency of the speaker in the given enclosure. Port design principles and how they integrate with overall cabinet (and speaker) designs are a very rigorous science where refinements are still being made.Port also refers to an input or output of some device, usually an electronic device. A SCSI connection is considered a port (often called a SCSI port), serial connections are ports, and so on.Finally port also refers to the concept of taking software written for one type of platform and converting to work with another platform. This is known as ‘porting.’ For example, when a software company decides they want their Mac based program to also be available for Windows users they can ‘port’ it over, which is usually much easier than writing entirely new code from the ground up, though there are also advantages to all new code.