alter: previously recognized as a “personality,” an alter is a new consciousness created by the brain in response to trauma. just like you, alters are their own 3-dimensional people with thoughts, personality traits, voices, likes and dislikes all distinct from one another. see Resources for information on different types of alters
introject: while many alters originate from within the body, sometimes they join the system with memories of their own, not previously experienced by the body or other alters. see Resources for information on different types of alters
fronting: being in control of the body and interacting with the world (talking, moving around, etc.).
co-fronting (aka co-consciousness): when multiple alters (generally no more than 2-3) front at the same time
switching: when one alter leaves front and another takes their place
host: the primary alter–the one who fronts most regularly and is generally associated with the body. generally alters will respond to the host’s name even if the host is not fronting
system: term for all alters + host collectively as a unit