Preface -- PART 1: To fear or not -- Disambiguating fear as an emotional state vs. threat detection. Molecular and Neural circuits of fear extinction. Psychological and theoretical elements on the concept of fear extinction. Neural circuit of fear extinction: psychophysiology -- PART 2: Individual differences in fear extinction -- The impact of sex differences and sex hormones on fear extinction. Impact of sleep on fear extinction. Impact of stress and exercise on fear extinction. Intersect between the intrinsic and extrinsic factors that modulate fear extinction -- PART 3: Psychopathology -- Fear extinction and its relevance to psychopathology. Developmental fear and its extinction imaging. Fear extinction and adult psychopathology -- Part 4: Therapeutics and neuromodulations of fear extinction -- Exposure therapy and other behavioral therapeutics targeting fear extinctioncircuits. Novel pharmacotherapeutics targeting fear extinction circuits. Reconsolidation and its link and impact on fear extinction. Technological advances in exposure therapy: virtual and augmented reality. Novel approaches using neurostimulation targeting fear extinction.