Let's deal with one subject right off: What is rattan? Actually, rattan is a natural plant product - it is grown in the moist, humid tropical regions of Asia and India. Bamboo grows there as well, but unlike bamboo, which has a hollow stalk, rattan is solid. In addition, bamboo is less flexible than rattan - which is good as this allows the maker to fashion it into all sorts of useful furniture objects.
As mentioned, rattan grows in tropical areas. After being harvested, the plant stalks are cut down into the lengths needed for the furniture. A reputable rattan grower will treat the plants harvested with chemicals - otherwise the rattan can become infested with a fungus that can discolor and eventually destroy the plant fibers. Less reputable harvesters will not treat the plants properly, and as a result you can have problems with it later.
This leads me to my first recommendation: unless you consider yourself an expert on the subject, make sure that you buy your outdoor rattan furniture from a reliable dealer. If you don't you may invest your hard-earned money on junk that will just not last, or look its best.
Since outdoor rattan furniture is a natural product, you should make sure that you do not leave your furniture outside sitting on floors or decks that have pools of water that do not drain away. Eventually the water can become absorbed into the rattan, causing it to swell, and gaps may appear in the frame or woven fabric of the back and sides.
Maintaining your outdoor rattan furniture is very easy: vacuum the dust and dirt from it, or use a warm, soapy cloth. If your furniture does get wet, it should be allowed to dry - thoroughly - especially before storing it away for the winter season.
Sometimes your outdoor rattan furniture requires more care than usual. In that case, you should take your furniture to a furniture repair expert. If you see small rough areas develop on your furniture, you can sand them lightly and then apply a finish or varnish. But if you've managed to crack the frame, or the weaving has holes in it - then you need to refer the whole matter to the pro of your choice.
Properly cared for, outdoor rattan furniture will give you many, many years of useful service. Rattan is used the world over for outdoor furniture. It is cool, clean, lightweight and does not require extensive maintenance. For the cost, it really is one of your best values in outdoor furniture.