A sealed envelope is a type of paper container used to hold and protect documents or letters. It is typically made from paper and has a flap that can be folded down and secured, often with adhesive or a sticker. Sealing the envelope helps ensure that the contents remain private and secure until they are opened by the intended recipient. Sealed envelopes are commonly used for personal correspondence, business communications, and official documents. They can vary in size, color, and design, and may also feature additional security measures, such as tamper-evident seals. The use of sealed envelopes is a traditional practice that dates back centuries.