The TCR β (T-cell receptor beta chain) is a crucial component of the T-cell receptor, which, together with the TCR α chain, forms the αβTCR on the surface of T cells. This receptor is responsible for recognizing and binding to antigenic peptide complexes presented by MHC molecules. The diversity of the TCR β chain is generated through a combination of random recombination of multiple germline gene segments, gene rearrangement, junctional diversity, N-region nucleotide insertions, and random pairing of α and β chains. These mechanisms collectively provide the TCR repertoire with immense diversity, enabling T cells to recognize a wide range of antigens.