Contact lenses come in various colors and for different purposes, and can either correct vision or be used cosmetically by placing them on the cornea. It is important to ensure safety and cleanliness when wearing contact lenses to avoid serious eye problems. Key safety rules include selecting lenses as directed by an eye specialist, not wearing them overnight or while bathing/swimming, changing them every 2-3 months, and removing them if any irritation occurs. Contact lenses provide closer vision than glasses and allow for convenience during sports.