Business Envelopes are the most popular style. They include the envelopes that businesses and organizations use the most to mail invoices and letters.
Catalog Envelopes (Open End) have the flap on the short side which allows for easy insertion. They're great for large-size documents and other materials.
Booklet Envelopes (Open Side) have the flap on the long side which allows for easy insertion. They're great for larger-size documents and other materials.
Announcement Envelopes are used for announcements, invitations, cards, brochures or promotional pieces. They come in two styles, Baronial Envelopes which have a pointed flap and are more traditional and formal; and the A-Style Envelopes which have a square flap design.
Offering Envelopes are used for church offerings and other times money needs to be collected. They come with either a standard flap or a remittance flap.