Computing

• Flag (computing), a true/false, on/off or open/closed indicator (Boolean variable)
• Command line flag, a modifier for a command line interface command
• FLAGS register (computing), a CPU register on x86 systems
• Fiber-Optic Link Around the Globe (FLAG), an undersea fiber optic cable
• To alert admins on a message board that a post needs to be moderated
• Industry
• F.L.A.G. (Fabbrica Ligure Automobili Genova), an Italian automobile manufacturer c. 1906
• FLAGS (Far North Liquids and Associated Gas System), a natural gas pipeline in the North Sea
• Flag and pennant patterns, in technical analysis
• Mathematics
• Flag (geometry), part of a polygon, polyhedron or higher polytope
• Flag (linear algebra), an increasing sequence of subspaces of a vector space