Business Envelopes: These are standard-sized envelopes typically used for professional correspondence, mailing invoices, letters, and documents. They usually come in standard sizes like #10 (4.125" x 9.5") or #9 (3.875" x 8.875") and can be either plain or with a window for address visibility.

Window Envelopes: Window envelopes have a transparent window through which the recipient's address printed on the letter inside can be seen. They are commonly used for bulk mailing and business correspondence to save time on addressing.

Catalog Envelopes: These larger envelopes are designed to accommodate catalogs, brochures, and other large documents without folding. They come in various sizes and are often sturdier than regular envelopes to protect contents during mailing.

Square Envelopes: Square envelopes have an equal length and width, giving them a unique look compared to standard rectangular envelopes. They are often used for invitations, greeting cards, and special announcements.

Padded Envelopes: Also known as bubble mailers or cushioned mailers, padded envelopes have built-in padding, usually bubble wrap or foam, to protect fragile items during shipping. They come in various sizes and are popular for mailing small electronics, jewelry, or documents.

Security Envelopes: Security envelopes have patterns printed on the inside to obscure the contents and prevent reading through the envelope. They are commonly used for confidential documents, checks, and sensitive correspondence.

Colored Envelopes: These envelopes come in a variety of colors beyond the typical white or manila. Colored envelopes are often used for special occasions, marketing materials, or to match branding themes.

Tyvek Envelopes: Tyvek envelopes are made from a durable, tear-resistant material (Tyvek) that is lightweight yet strong. They provide excellent protection against moisture, punctures, and tearing, making them suitable for shipping important documents or items.

Self-Seal Envelopes: These envelopes have an adhesive strip on the flap that allows for easy and quick sealing without the need for moisture or licking. They are convenient for high-volume mailing and are available in various types like business envelopes or padded mailers.

Airmail Envelopes: Airmail envelopes are lightweight and typically have distinctive blue and red markings or patterns, indicating they are designed for international airmail delivery. They often include space for customs declarations and are used for sending letters or documents abroad.