1. What is a Port Expander: A port expander is a device that allows one port on a computer system to connect to multiple devices. There are two basic forms of port expanders: internal and external. An internal expander has a connection inside the computer, typically on the motherboard, and the only part the user sees is the expansion plate containing multiple ports. An external device plugs into the existing port and then has multiple places to connect. When not part of a computer system, these devices are commonly known as splitters.
2. Types of Port Expanders
USB Port Expander
FireWire Port Expander
Ethernet Port Expander
VGA Port Expander
SCSI Port Expander
Serial Port Expander
Video Port Expander
Audio Port Expander
DVI Port Expander
DB-25 Port Expander
SATA Port Expander 3. Are they generic,or can work on multiple computers
There are no specific types of ports for different computers in todays technology. All the computers from PC to Mac have all the same ports on them. Port Expanders will work for just about any PC.
4. Advantages and Disadvantages
advantages of using port expanders are that you get more ports to use. If you ever run out of VGA ports, usb, SCSI ,or even Ethernet ports. You can always buy a port expander for it whether it be internal or external. Also In Some cases port expanders are cheaper than getting an equal number of "real" ports.
Disadvantages are a lot of them are external and they can get in the way of you working. Also could use more power and if your power source isn't good enough it could cause problems when you add more devices it consumes more power. The power source Milli amperage is limited theres only so many extra ports you can use. And if you over load the power source the computer wont turn on. Until you unplug them. And I read that it can possibly destroy the power supply but rarely.