This document discusses mental illness, including common types like depression, anxiety disorders, and schizophrenia. It notes that approximately 1 in 4 people will experience a mental illness in their lifetime. Mental disorders can cause abnormal thoughts, emotions and behaviors and impact daily life and relationships. Diagnosis involves physical exams, lab tests, and psychological evaluations to determine the appropriate illness and treatment, which may include medication, therapy, and community support programs. Theories like Maslow's hierarchy of needs and conflict theory are discussed in relation to mental illness.