What is a portable dishwasher?
Simply, a portable dishwasher is a dishwasher that can be moved around; it is not permanently installed underneath a counter. Most portable dishwashers are very similar to standard dishwashers in appearance and operation, but they have a few key differences:

Caster wheels
Portable dishwashers usually utilize caster wheels instead of legs so the dishwasher can be easily rolled from place to place.

Finished top and sides
Unlike built-in dishwashers, portable dishwashers have completely enclosed sides and the top can be used as a work surface, so it looks nice standing alone, and it minimizes noise during the wash cycle.

Temporary water and drain connections
Built-in dishwashers are "plumbed in" with permanent connections to water inlet and drain lines. Portable dishwashers come with a drain hose that can be moved from place to place (usually they are drained to the drain in your sink) and an adapter to connect to a water line. This water line connection is usually in the form of a quick-connect adapter, which connects to your sink faucet.

Why should I get a portable dishwasher?
Portable dishwashers are great for situations in which normal dishwashers won't work. For example, a portable dishwasher can be stored away in a closet or pantry and only rolled out when needed. Of course, the fact that portable dishwashers do not require a permanent undercounter installation is another attractive feature. You can have a dishwasher without losing cabinet space or paying for a costly installation.

Can I install a portable dishwasher permanently?
Yes, most portable dishwashers can be installed permanently, but keep in mind that a portable dishwasher is designed primarily for portable use. To install a portable dishwasher permanently under your counter would require some modifications to the unit and may void the warranty.

What features should I look for in a portable dishwasher?
Look for the same features in a portable dishwasher that you would in a built-in unit. Check the number of cycles, whether the unit has a dry cycle or not, whether the interior is stainless steel (which will be more durable) or not. Another consideration is the width of the dishwasher. Generally, portable dishwashers come in either 18" and 24" widths. The 18" wide portable dishwashers will be smaller on the outside, but will also generally have less capacity on the inside than the 24" wide portable dishwashers.