Generation-one Advanced Format, 4K sector technology, uses the storage surface media more efficiently by combining data that would have been stored in eight 512-byte sectors into one single sector that is 4096 bytes (4 KiB) in length.
Having a huge number of legacy 512-byte-sector-based hard disk drives shipped up to the middle of 2010, many systems, programs and applications accessing the hard disk drive are designed around the 512-byte-per-sector convention.