In times gone by, indoor rugs were indoor rugs and outdoor rugs were outdoor rugs. That distinction has become blurred as time has gone by owing to the development of high quality polypropylene rugs. Polypropylene is a synthetic polymer material derived from petroleum byproducts and is also known by the trademark name Olefin. Not surprisingly, they are often marketed as 'indoor-outdoor rugs'.
Polypropylene rugs, being synthetic, tend to shrug off stains and the fading effects of sunlight better than natural fibers, and can shrug off a rain shower or hosing off without developing mold or mildew, assuming they get a reasonable chance to dry.
However, they tend to cling to greasy stains, so they probably aren't a good bet to place under your barbecue grill. Still, they can withstand the routine spills of children and tipsy guests.
They can be manufactured in a tightly looped structure that can easily be mistaken for a natural fiber, and are not the 'plasticy' braided sort of thing found at my Grandma's back door. Instead they are soft and might even be considered somewhat plush. They are available in a huge variety of styles, sizes and shapes, not to mention bright and attractive colors.
They can be found in a wide variety of motifs, as well. From southwestern styles in bright colors to a Persian look in more muted tones, not to mention solids, your imagination is probably the limit as to what you can find. A trip to some local carpeting stores or home centers will give you a broad selection. If you don't find just what you want in those venues, a trip on the internet will amaze you with the possibilities.
For outdoor use, they are typically found as area rugs, and in this mode they are easily picked up and machine washed. They can endure many washings and still look as good as new. They are of a substantial weight, however, and you might want to consider taking them for a wash in the big, heavy duty washing machine at the laundromat.
However, for day to day spills, they can be cleaned up with the application of some soap and water with a soft brush, rinsed off with a garden hose and left to air dry. An area rug is also easily rolled up and taken indoors for the winter. For all its gleaming whiteness, snow manages to pick up a good deal of grime, and as it melts that grime will be left to soak into your rug. No point in subjecting it to avoidable hazards, is there?
All of the qualities listed above make them desirable for those areas of the home where dirt and spills are to be expected; say entry ways and the kitchen in particular. However, they aren't as soft or 'cozy' as wool, for example. Unless you have chronic spillers roaming in your living room or family room, you probably will want to go with some other fiber.
For outdoors or indoors, or in a transition area such as a foyer, polypropylene rugs have much to commend them.
