Blu-ray Disc recordable (or BD-R) refers to two optical disc formats that can be recorded with an optical disc recorder. BD-R discs can be written to once, whereas BD-RE can be erased and re-recorded multiple times. Disc capacities are 25 GB (23.31 GiB) for single-layer discs and 50 GB (46.61 GiB) for double-layer discs.