Personality refers to enduring patterns of thinking, feeling and behaving that distinguish individuals. It involves physical, mental, emotional, social and spiritual aspects. Personality can be assessed through projective or objective tests. Major approaches to studying personality include psychodynamic (focusing on unconscious processes), humanistic (focusing on self-actualization), and biological factors. Personality disorders are inflexible patterns that cause distress, with clusters including odd/eccentric, dramatic/erratic, and anxious/fearful types. Therapies include psychotherapy, behavior therapy, biological treatments like drugs, and electroconvulsive therapy.