Different types of hardware connections
The scart plug is used for video and audio connections. It is designed to carry analogue standard definition content, an example of its use would be plugging a games console into the TV.
A Video Graphics Array (VGA) connector is a three-row 15-pin connector. The 15-pin VGA connector is found on many video cards, computer monitors, and some high definition television sets. It is basically a graphics display system for PC's. An example of using a VGA would be plugging a monior into a computer.
Line in/ Line out
Line out - A type of connector found on audio devices used to attach audio components, such as speakers. This is commonly used when are plugging in headphones to a computer etc.
Line in - A type of connector found on audio devices to attach a device, such as a microphone, for recording audio. Line-in can be analog or digital. Digital line-in is also called optical line-in.
Optical Audio Cable
Also known generically as an "optical audio cable", its most common use is in consumer audio equipment (via a "digital optical" socket), where it carries a digital audio stream from components such as minidisc, CD and DVD players, DAT recorders, computers, and modern video games consoles, to an AV Reciever that can decode the stream of audio and output it through a set of loudspeakers.
A FireWire connection lets you send data to and from high-bandwidth digital devices such as digital camcorders, and it's faster than USB. FireWire is a way to connect different pieces of equipment so they can easily and quickly share information.