Coil binders are a type of binding system used to hold together multiple sheets of paper. They consist of a continuous plastic or metal coil that is threaded through holes punched along the edge of the pages. This method allows the pages to lay flat when opened, making it ideal for notebooks, reports, and presentations. The coil binding process is often done using a binding machine, which punches the holes and inserts the coil. This binding style is popular in schools and offices due to its durability and flexibility, allowing for easy page turning and the addition or removal of pages as needed.