1) A data licence sets out how data can be reused and attributed. It is recommended that all data intended for reuse have a licence, whether open or restrictive, to promote safe and proper reuse. 2) The Creative Commons suite of licences are commonly used with 6 options ranging from most open to most restrictive. The CC BY licence allows for reuse and redistribution with attribution. 3) Applying a clear licence to data promotes safe data sharing and prevents unintended misuse by clarifying how others can access and use the data.