Modern printing has had a huge impact on stamp production and philately. Experienced collectors and philatelists are now finding themselves having to learn new philatelic terms and definitions. For example, many new stamps are die-cut. What does that mean?
Simply put, die-cutting is a method of stamp separation designed for self-adhesive stamps. Older, gummed stamps are perforated so that you can separate them one from another (see article: FAQ-What are stamp perforations? ). Modern self-adhesive stamps are very rarely perforated, instead they are die-cut. In other words, a metal die cuts out the sides of the stamps.