An important distinction to make is that though there are a variety of different methods for connecting MIDI devices. Most of these methods use the same cable. The only aspect that changes is the layout of the connector soldered to the end. MIDI data is fairly simple numerical data with a low electrical load. As a result, it can be transmitted along basic three-wire cable.
This is the most common cable used in MIDI connections and is often referred to simply as a "MIDI" cable. It uses a round connector with a protruding metal ring. Each of the five pins inside carries a different aspect of the note data. There are variants on this connector for specific applications, an eight-pin version allows the connection of multiple MIDI interfaces, and a nine-pin version is used to sync the time-codes of studio equipment using the ADAT protocol.
A common connector on early MIDI-enabled PCs, the Gameport cable was intended to allow the connection of MIDI keyboards and synthesizers to early PC sound-cards, most of which had a 15-pin D-Sub connector. This cable has largely been superseded with the growth of USB connectors since the year 2000, but it was the only option for many early-adopters of PC sequencing software.
Though not strictly a musical interface cable, most MIDI instruments now include a USB port in parallel to MIDI connectors. Since most PCs no longer include a gameport on the sound-card, users would have to purchase a separate USB-to-MIDI interface to allow for connection to a PC. Negating the need for a stand-alone interface makes USB-ready controllers and attractive prospect for new buyers. The USB cable is also much faster than standard MIDI cable for copying patches and backing up sound-banks to the computer's hard drive.