A port expander is a hardware device designed to allow the computer to utilize more than one device on a signal port at one time. There are two types of port expander they are internal and external. Internal port expanders are connected inside the computer, usually they are on the motherboard and the only part the user sees is the expansion plate that contains multiple ports. The external port expander will plug into the existing port and then have multiple connectors. The most common of these port expander are USB and Ethernet ports. There are numerous types of ports that have available port expanders. Here is a list that I have compiled:
Ethernet port expander
Firewire port expander
DB-25 port expander
Serial port expander
USB port expander
VGA port expander
DVI port expander
SCSI port expander
Audio port expander
Video port expander
Microphone port expander
RS-422 port expander
Modbus serial port expander
SATA port expander
All port expanders are generic they will work on any computer as long as the computer has a port for that expander. There are advantages and disadvantages to using port expanders. One advantages are to using a port expander is that you can get more available ports to use and plug things into. Having an external port expander would have an advantage by you could unplug the port expander form one computer and move it to a new computer. The major disadvantage to a port expander is that the original port still only has its original bandwidth. Say