The term "Halo" encompasses a remarkably diverse range of meanings, most commonly referring to an optical phenomenon, a religious symbol, or the hugely popular Halo science-fiction video game franchise (active from 2001 to 2021), which also inspired a 2022 TV series adaptation. Beyond gaming, the name is frequently found in music, with numerous songs bearing the title, most famously Beyoncé's hit from 2008, and also appears in films, fictional characters, and various other artistic works.
"Halo" also designates significant concepts across professional fields; for instance, the military uses "HALO jump" for high-altitude parachuting and "Mil Mi-26 Halo" for a heavy transport helicopter, while medicine recognizes the "Halo effect" as a cognitive bias. Furthermore, the term describes astronomical structures like galactic halos, the future Habitation and Logistics Outpost (HALO) module for space, and serves as a crucial safety device in racing cars, alongside its use in the names of historical figures such as Kurdish ruler Halo Khan Ardalan (1590–1616) and various geographical locations.