Asking me what types of orchids there are is like asking me what types of people there are. Well, there are tall and short people, smart people and not-so-smart people, introverts and extroverts, people with different skin colors, and people from different parts of the world. Likewise, you will find many different types of orchids—different colors, species and hybrids, miniature and standard-sized, all different genera from different parts of the world. So I will narrow the question a bit, and look at it in terms of the orchids you will likely to buy and grow.
The main characteristic of this type of orchid is its very pleasant aroma, which means you will likely smell it even before you see it. The pure white flowers release their scent at night, are frequent bloomers, and can bloom all year long in many places. They are a small but showy type of orchid, and their leaves are long, reed-like in shape, and light green in color. They are also easy to grow and are low-maintenance flowers.
Disa is a genus of beautiful plants with rather triangular flowers, often red. They require VERY different care than other types of orchids, so it's easy to kill them if you don't know what you're doing. In particular, they like it wet and should never dry out. The best-known Disa is Disa uniflora, which in South Africa is known as the Pride of Table Mountain.
The type of potting medium being used can also affect your plant's water requirements. Bark has a tendency to dry out more rapidly than sphagnum moss, for instance. It is important to remember, however, that even when the surface of your pot is dry, the root area may remain moist. Poke your finger or a regular wooden pencil an inch into the pot; if it feels moist to the touch or if the pencil looks moist, do not add additional water. The potting medium should always be damp, but not soggy—neither should it be allowed to get extremely dry.
Check your water. For a long time, serious growers insisted that orchids could only be watered with rainwater. Nowadays, most people just use tap water, and this is fine. However, be aware that treated water may have higher salt content, and some water is high in calcium. If you see deposits forming on your plants, you should seek out a new water source.
These orchids can be planted in orchid bark, moss or a mix (mixes might include bark, small rocks, moss, sponge rock, and even cork). Don’t even think about planting them in the soil. If your orchid is planted in bark you’ll need to water it more often than if it’s planted in moss. The bark will help the water drain with ease where the moss will hold the moisture longer. I prefer the bark or mixes which are predominantly bark because the watering is much easier for me to get right.
Water thoroughly. When you do water, do it like you mean it. Different growers have different rules, but many professional growers turn on their sprinklers for 8 or more minutes. Successful home-growers sometimes dunk their plants, pots and all, into a bucket or sink of water. Some varieties, such as vandas, can be left floating in water for a surprisingly long time. The idea is to make sure the velamen is completely saturated. You want tiny droplets hanging on the roots after watering. This means the plant is completely hydrated.