BRD2 (Bromodomain and Extraterminal Domain Protein 2) is a member of the BET protein family, characterized by two tandem bromodomains (BD1 and BD2) that recognize and bind acetylated lysine residues on histones, thereby regulating gene transcription. BRD2 plays crucial roles in various physiological processes, including cell cycle regulation, embryonic development, neural tube closure, and immune responses. It interacts with transcription factors such as E2F1 and E2F2 to activate the expression of cell cycle-related genes and promote the G1/S phase transition. Additionally, BRD2 is involved in chromatin remodeling and the fine-tuning of gene expression. In disease contexts, BRD2 is implicated in the development, progression, and drug resistance of various cancers, such as colorectal cancer, where it modulates tumor suppression via the AKT-FOXO3/4 signaling pathway. BRD2 is also associated with metabolic disorders, neurodevelopmental conditions, and inflammatory diseases. Given its key role in gene regulation, BRD2 has emerged as a promising therapeutic target, with ongoing research into BET inhibitors.