Envelopes

An envelope is a flat, typically rectangular container used to enclose a letter or small document for mailing or delivery. Made primarily of paper, envelopes may also be fabricated from plastic or composite materials. They come in a variety of sizes and styles to fit different contents and postal requirements. Common regional sizes include the United States standard #10 envelope (about 4.125 by 9.5 inches), Europe’s DL (110 by 220 mm), and larger C5 or C4 formats designed to hold A5 or A4 sheets. Some envelopes are windowed to expose the address printed on the contents; others are opaque for privacy or security.

Materials and features vary widely. Writing-quality papers, recycled fibers, manila or kraft stocks, and coated or uncoated finishes are used depending on purpose. Closure methods include moistenable gummed flaps, self-sealing adhesives, and peel-and-seal options. Security envelopes are designed with patterns or tinted linings to obscure the contents.

History and development: envelopes have ancient precursors in papery wrapping, but modern paper envelopes with gummed flaps emerged in Europe in the 17th to 19th centuries and expanded with mass production and postal systems.

Uses and design considerations: envelopes protect contents, assist in handling and sorting by postal systems, and support addressing through features like windows or preprinted information. Environmental considerations increasingly emphasize recycled content, minimal coatings, and recyclability.

Manufacture and customization: production involves cutting sheets to size, forming flaps, applying adhesive or coatings, and adding printing or window openings as required. Variations address institutional, commercial, and personal mailing needs.