Contact lenses are made out of various different kinds of plastic. There are however only two main groups of contacts. They are soft contact lenses and gas permeable contact lenses.
Soft contacts are the more popular of the two. They are thin and gel-like and more flexible then gas permeable contacts. Soft contacts are also better at staying in place on your eye and thus make a better choice for people that participate in sports or lead an active life.
The soft styles come in three varieties. They are daily wear, single use and extended wear. Single use lenses are exactly what they sound like. They are intended to be used a single day. These contacts are the most expensive of the three but do not require any special solutions. Daily wear contacts are also disposable and are designed to be worn anywhere from one to four weeks. These contacts require daily cleaning and are thicker then the daily wear styles. Extended wear are designed for up to a week of continuous wear even while sleeping. These contacts do have some health concerns from most doctors. The cornea does not get enough oxygen while continuously wearing them and corneal complications including infections have been common.
Gas permeable contacts are stiffer and have a smaller diameter then soft contacts. This allows for more oxygen to reach the corneas and thus have less cornea irritation. These contacts are at first less comfortable than soft lenses. They take awhile to get used to but when people stop wearing them they will have to re-adapt.
To learn more about different styles of contacts, and to find some cheap contact lenses, please visit this link.