A ring binder is a type of folder used to organize and store loose sheets of paper. It features a mechanism with metal rings that can be opened and closed, allowing users to add or remove pages easily. Ring binders come in various sizes and materials, making them suitable for different purposes, such as schoolwork, office documents, or personal projects. These binders often have a cover that can be customized, allowing users to insert a title page or label. They are commonly used in conjunction with dividers and sheet protectors to further enhance organization and protect important documents.