Summarize this article in one sentence.
Whether your contact lenses are prescribed to correct your vision, or whether they're decorative, your contacts will be one of many kinds. Most contacts are soft contacts, which means that they are flexible. Soft lenses allow oxygen to pass through to the cornea. Soft contacts are disposable, and can be worn for one day (daily disposable), 2 weeks, or 4 weeks. Lenses can also be hard, which means they are rigid and breakable. These contacts are also known as RPGs or "rigid gas permeable."   Contacts can also be bifocal. Even though contacts can be worn for many days, it's best to remove them each night as you sleep. RPGs may be the best choice of contact lenses for someone with allergies. Even though RPGs once had a reputation for "popping out" of the eye, newer models have greatly improved the comfort level and sustainability. Soft lenses have a greater chance of sliding up underneath the eyelid, or getting folded while still in the eye. People who wear contact lenses have an increased risk of infection to the cornea. Wearing contacts in a way other than prescribed - e.g. wearing daily contacts for a week, or wearing them overnight - may result in temporary, or even long-term damage to the cornea.  Soft, extended-wear contacts have the highest risk of developing protein build-up on the lens. This may result in lens-related allergies. Infections often result from poor lens cleaning as well as misuse. Even though contacts are popular and easy to wear, there are still some hazards associated with wearing contact lenses. Eye infections, scratching the cornea, and allergic reactions as demonstrated by itchy, red, watery eyes are among the most common results from wearing contacts, even if you follow all the guidelines.  If you choose to wear contacts, you need to also be able to commit to taking care of the contact lenses as well as your own eyes. If you're wearing contacts as a decorative accessory, make sure your lenses are FDA-approved. Anyone selling contact lenses is required to get a prescription from your doctor - even if you don't require prescriptive lenses! The reason for this is that contact lenses must be fit to your eye, and contacts that don't fit properly could result in damaging your eye or even causing blindness. If you're someone who frequently gets eye infections, has chronically dry eyes, or serious allergies, you may not benefit from wearing contact lenses. If you work in an area with a lot of particle matter in the air, you might also want to avoid contacts.  If you're the kind of person who has a hard time doing the daily washing and caring for contacts that they require, you might want to avoid wearing contacts. Wearing contact lenses means that you'll have to take them out in the evening. If you have a schedule where your evenings are greatly varied, you might want to stick to glasses. If you're planning to just wear decorative colored lenses, make sure you bring a case to store them in when your eyes are tired and you need to remove your lenses. Always wash your hands well with soap and water before touching your contact lenses. It's recommended that you clean your contact lens case every day, and change your case at least once every 3 months.  Never share your colored contact lenses with someone else. Homemade contact lens cleaning solutions have been linked to serious eye infections. Always purchase FDA-approved saline and cleaning solution. Take out your contact lenses and call your doctor if you start to notice signs of eye discomfort or distress. If your eyes start to hurt, itch, or become red and watery, you may have an eye infection or injury. If your eyes may become overly sensitive to light, or you have blurry vision, call your doctor.  Your eye may feel scratchy, as if there's something stuck in it. This can be an indication of a scratch on your cornea. Always start by taking your contact out when you notice these signs.

Summary:
Learn more about different types of contacts. Wear contacts as directed. Learn more about risk factors associated with wearing contacts. Check your medical history. Keep your contacts clean. Notice changes in your eyes.