The androgen receptor (AR) is an X-linked intracellular receptor that functions as a ligand-activated transcription factor mediating cellular responses to androgens and other steroid hormones. AR operates through multiple mechanisms including DNA binding, transcriptional activation of RNA polymerase II-dependent genes, and molecular adapter functions within membraneless organelles and chrX complexes. The receptor exhibits dual signaling capacity, responding to both androgenic and estrogenic stimuli through distinct intracellular pathways. AR mutations cause a spectrum of androgen-insensitivity disorders ranging from complete androgen insensitivity syndrome (CAIS) to partial forms (PAIS), resulting in phenotypic variation from female external genitalia to hypospadias depending on residual receptor function. Loss-of-function AR mutations also underlie X-linked spinal and bulbar muscular atrophy (SBMA), where polyglutamine expansions impair motor neuron survival. Conversely, AR dysregulation contributes to hereditary prostate cancer development through enhanced or aberrant transcriptional activity. Clinically, AR status is fundamental to sex differentiation, fertility, bone health, and muscle maintenance. AR-targeting therapeutics are essential for managing androgen-insensitive conditions, SBMA, and androgen-dependent cancers, making AR one of the most therapeutically relevant nuclear receptors in clinical medicine.