Depersonalization-derealization disorder (DPDR) is a dissociative disorder characterized by persistent or recurrent episodes of detachment from one's self (depersonalization) or surroundings (derealization), while reality testing remains intact. Affecting approximately 1-2% of the general population, DPDR remains underrecognized in clinical settings and is frequently misdiagnosed as anxiety or depression. This paper provides a comprehensive review of the current understanding of DPDR, including its diagnostic criteria, epidemiology, etiology, neurobiological underpinnings, and treatment approaches. Emerging evidence from neuroimaging studies points to a fronto-limbic inhibitory mechanism, whereby prefrontal regions suppress limbic and autonomic responses to emotional stimuli, resulting in the characteristic emotional numbing. The disorder is strongly associated with childhood interpersonal trauma, and cognitive-behavioral therapy currently represents the best-documented treatment approach. Pharmacological interventions have shown limited efficacy, though promising avenues are emerging. The paper synthesizes findings from phenomenological, neurobiological, and clinical studies to present an integrated model of DPDR and identifies priorities for future research.