Intel Quick Sync Video is Intel's brand for its dedicated video encoding and decoding hardware core. Quick Sync was introduced with the Sandy Bridge CPU microarchitecture on 9 January 2011, and has been found on the die of Intel CPUs ever since.
The name "Quick Sync" refers to the use case of quickly transcoding ("converting") a video from, for example, a DVD or Blu-ray Disc to a format appropriate to, for example, a smartphone. This becomes critically important in the professional video workplace, in which source material may have been shot in any number of video formats, all of which must be brought into a common format (commonly H.264) for inter-cutting.
Unlike video encoding on a CPU or a general-purpose GPU, Quick Sync is a dedicated hardware core on the processor die. This allows for much more power efficient video processing.