A paper envelope is a rectangular, flat pouch made from paper, designed to contain and protect documents or items for mailing or storage. Typically, it features a fold-over flap, which can be sealed with adhesive or a gummed strip. Paper envelopes come in various sizes, with options like standard, padded, or specialty designs, offering choices for different purposes. They are often made from recyclable, eco-friendly materials and can be plain or decorated with designs, logos, or patterns for branding or personal use.