DiSC is a personality assessment tool that categorizes people into four primary disc communication styles: Dominance, Influence, Steadiness, and Conscientiousness. The Dominant style is characterized by direct, decisive, and assertive communication, while the Influence style is outgoing, optimistic, and persuasive. The Steadiness style values cooperation, sincerity, and loyalty, while the Conscientiousness style prioritizes accuracy, attention to detail, and planning.