An alter is a “dissociated self state” (“Alters in Dissociative Identity Disorder.” Dissociative Identity Disorder Research). The book refers to Milligan’s alters as “personalities” or the “people inside.” In DID, each alter has its own, unique sense of self and can display different behavioral characteristics, values, feelings, skills, and abilities. Each alter may even have a specific age, gender, sexuality, and ethnicity that differs from the “host” self and from the other alters. Thus, in Milligan’s case, Arthur was English, Ragen was Yugoslavian, and their speech was accordingly accented, although Milligan himself was American; similarly, April, Adalana, and Christene were all feminine alters; and Tommy exhibited incredible skill with electronics and escape mechanisms, which the other alters and Billy himself did not. Alters may or may not be aware of and communicate with each other; thus, Arthur and Ragen were aware of and communicated with some but not all the other alters. An individual experiencing DID may or may not be aware of the presence of alters; Milligan was initially unaware of his alters. All the alters within an individual are known collectively as a system.