This Practice Note looks at what constitutes a green bond and covers: (1) green use of proceeds bonds, (2) green use of proceeds revenue bonds, (3) green project bonds, (4) secured green bonds, (5) the components of the Green Bond Principles (use of proceeds, process for evaluation and selection, management of proceeds and reporting), (6) use of external assurance to confirm compliance with principles, (7) methods of verifying green credentials, and (8) how the green bond market is developing.