To be fair, the definition of a kilobyte actually changed recently (2007) thanks to HDD and SSD manufacturers using the term constantly and incorrectly. The definitions are as follows:
1 Byte (B) = 8 bits (bit/b)
1 Kilobyte (KB) = 1,000 Bytes
1 Megabyte (MB) = 1,000,000 Bytes
1 Gigabyte (GB) = 1,000,000,000 Bytes
1 Terabyte (TB) = 1,000,000,000,000 Bytes
1 Kibibyte (KiB) = 1,024 Bytes
1 Mebibyte (MiB) = 1,024 KiB = 1,048,576 Bytes
1 Gibibyte (GiB) = 1,024 MiB = 1,073,741,824 Bytes
1 Tebibyte (TiB) = 1,024 GiB = 1,099,511,627,776 Bytes
So, 1TB is now actually ~91% of a TiB (a true terabyte).