Magazine filler is a term used to describe the content of magazines, which can include items such as ammunition, advertisements, and inserts. Ammunition, or AMMO, is a four letter word that refers to bullets, cartridges, and other items used in firearms. ADS, or ADS, is a three letter word that refers to promotional materials used to advertise products or services. Inserts, or INSERT, is a six letter word that refers to additional materials that are placed inside magazines, such as coupons, flyers, and brochures.