Diversity of orchids is absolutely amazing. Orchids belong to Orchidaceae family, which is the largest family of flowering plants, with at least 24,000 different species. It is not surprising, that orchid flowers are extremely various; they could be of any colour you can imagine, and their shape and size may very much differ among different species and genera as well. Flowers of a great number of orchids look really gorgeous.
In addition, many of them have very nice fragrance, which is also different among different species. Some orchids, for example Stanhopea, are so fragrant that their owners have to keep them outside when those orchids are blooming, because the fragrance is tremendously strong. Some orchids, for instance Brassavola orchids, smell at nocturnal time, which is wonderful. It is also interesting that the flower smell of certain orchids, for example Bulbophyllum, is quite repulsive, because natural pollinators of these orchids are flies feeding on rotten meat. Nevertheless, many of such orchids are valuable items for many orchid collectors.
Moreover, different orchids bloom in different seasons. It is possible to collect a combination of certain species or hybrids, which will be blooming one after another all year-round. Besides, there is a group of orchids prized for its ornamental foliage, rather than flowers, so-called group of jewel orchids.
Although, there are some terrestrial orchids, as jewel orchids for example, almost all orchids grown indoors are epiphytic plants, which grow in natural conditions on trees rather than on ground. This doesn't mean that orchids are parasitic; instead they use photosynthesis for energy like all green plants, and collect nutrients from plant debris or dust and water from moist air or the substrate. They attach to the trees and use them only as a physical support, with the main purpose to be closer to sun, because in a tropical forest it is almost impossible for herbaceous plants to survive under dense tree crowns. Perhaps, that is the main difference between orchids and majority of common house plants, though there are other epiphytes among house plants, for instance epiphytic cacti.
The first thing you should remember if you grow epiphytic orchids is that they must not be grown in soil, because it is not natural to them, and they will sooner or later die in such conditions. There are many different potting medium for orchids, but tree bark will do in most cases, and you can buy it in any gardening store.
As I said earlier, orchids are very various plants, which may very much differ in their care requirements. For instance, there are orchids which require bright light to grow well and flower regularly, but others like shady conditions; some orchids can grow and even bloom during the whole year, but others need a certain period of rest. So the second important thing you should consider is what particular type of orchid you grow. Then you can easily find info about growing requirements for this type of orchid, and eventually give your orchid all proper conditions to grow in.
Phalaenopsis hybrids are likely the most well-known orchids, which you can grow easily, but also there are many other orchids which can be grown at home without too much difficulty. Today, most orchids for sale in shops are hybrids which often have less strict requirements for growing at home than natural species. However, there are many different orchids which are very difficult to grow indoors, for example even some Phalaenopsis species might be very difficult to take care of in home conditions. Such orchids are usually grown by some sophisticated collectors, who have cultivated different orchids for a long time.
So orchids are very beautiful and diverse plants, which deserve to be a real beauty of every house, but to grow orchids successfully you should keep in mind that these little beauties are epiphytic plants, and you should also know what type of orchid you're going to grow to care for that appropriately.