What is a "pannier"?

A pannier is a type of bag or basket that is designed to be attached to a bicycle or motorcycle, typically on either side of the vehicle's rear wheel. It is used to carry items while riding, such as groceries, books, or other belongings. Panniers can be made of a variety of materials, including canvas, nylon, or leather, and may be waterproof to protect their contents from the elements. Some panniers have additional features such as reflective strips for increased visibility, and compartments for organizing items. They come in a range of sizes and shapes to suit different needs and preferences.