When the Blu-ray standard was introduced in the mid-2000s, it was made to support a maximum resolution of 1080p or Full HD. Ultra HD Blu-ray is a relatively new format in comparison but is distinguished by its ability to support 4K or Ultra HD resolution. Most new Blu-ray players support Ultra HD Blu-ray playback. It is important to note that UHD Blu-ray is not backwards compatible with standard Blu-ray players so an appropriate 4K UHD Blu-ray player is required for playback.