A mailbox is a container used for receiving and sending mail. It is typically placed outside homes or businesses, allowing postal workers to deliver letters and packages. Mailboxes can be made from various materials, such as metal or plastic, and come in different shapes and sizes. They often have a flag that indicates when there is outgoing mail. In many countries, mailboxes are part of the postal system, which includes organizations like the United States Postal Service or Royal Mail. These systems ensure that mail is collected, sorted, and delivered to the correct addresses. Mailboxes help facilitate communication and the exchange of information between people.