The size and shape of the flaps and type of seams combine to form six main types of envelopes used for the bulk of non-specialty applications.
- A-Style or Announcement Envelopes
Open side envelopes with square, often deep flaps and side seams. Sometimes with deep pointed flaps and diagonal seams.
- Baronial Envelopes
Open side, almost square envelopes with pointed flaps and diagonal seams.
- Booklet Envelopes
Open side envelopes with small square flaps and side seams.
- Catalog Envelopes
Usually open end envelopes with wallet style flaps and center seams.
- Commercial Envelopes
Open side envelopes with commercial style flaps and diagonal seams. The typical #10 envelope for business and personal mail is a commercial style envelope. The Monarch is a variation of the #7 3/4 envelope but with pointed flap.
- Square Envelopes
Large square flaps and side seams.
The links for each style go to a gallery showing the relative size of different envelopes along with dimensions for common envelopes sizes and their enclosures.