A mailbox is a container used for receiving and sending mail. Typically found outside homes or businesses, mailboxes are designed to protect letters and packages from weather and theft. They come in various shapes, sizes, and materials, such as metal, plastic, or wood. In many countries, mailboxes are marked with a flag to indicate outgoing mail. In the United States, mailboxes are often placed at the curb for easy access by postal workers. The United States Postal Service (USPS) has specific regulations regarding mailbox placement and design to ensure efficient mail delivery. Mailboxes can also be found in communal areas, such as apartment complexes or office buildings.