Port replicators and docking stations both perform similar functions: they provide a central connection point for external devices that you can use with a laptop computer. If you use the laptop as a part-time substitute for a desktop computer, with an external monitor, keyboard, and mouse, you can connect them permanently to the port replicator or docking station along with a network connector, external speakers, a printer, and other external devices. A laptop mounting in a docking station can offer all the flexibility and ease of use that you expect from a desktop computer, with the added benefits of a portable system.
When you want to take the laptop with you, all you have to do is lift out the computer, or unplug a single connector; everything else remains in place. Many docking stations also have a security lock that requires a key to prevent unauthorized removal of the laptop from the dock.
Port replicators and docking stations are usually designed to match a specific make and model of laptop computer. The computer fits into the base and automatically mates the docking port connector on the back or bottom of the case with a connector built into the base unit, so it's essential that the dimensions of the case and the exact location of the docking connector are correct. The alternative is a universal port replicator that uses all of the laptop's input and output connectors.
Port replicators and docking stations may both use the same multipurpose connector, but there are some differences: a port replicator extends access to input and output connectors to a separate package that remains in place when the computer itself has been removed; a docking station can include space for built-in expansion cards (such as a video controller or a sound card), a CD or DVD drive, and an extra disk drive.
If you're using your laptop with an external monitor, some docking stations offer an important advantage: you can choose a graphics controller card to drive the monitor, instead of settling for the one built into your computer. If you're using the computer for intensive graphics or for high-performance games, this can make a big difference to the quality of the images on your monitor screen.
Most laptop manufacturers sell the docking stations designed for their computers through their Web sites or mail-order catalogs. You might also find a few makes and models at a large computer superstore.