Envelopes are essential tools for business communication and shipping. They are used to package and send letters, documents, and small items securely. Envelopes come in various sizes and materials, such as paper, plastic, or cardboard, making them suitable for different purposes. For example, padded envelopes provide extra protection for fragile items, while plastic envelopes are ideal for waterproofing and preserving documents. Envelopes are a practical and convenient option for businesses and individuals looking to send mail or packages efficiently.