According to the International System of Units (SI), Kilobyte denotes multiple of a singular unit called as a byte and value of one byte is 1000 bytes since a kilo is equivalent to 1000. One kilobyte is written as 1 kB.
Binary system has been used since the inception of early computers with reference to system memory. Metric units, including kilo, mega and giga began to be used in computer industry, Computer memory uses binary system and hence 1kB is equal to 1024 bytes in some of the sections of information technology. The binary style of denoting memory for RAM, sizes of CPU cache, file sizes and capacities of storage disks.
Unit of kB is used to mention the rates of data transfer, speed of media transfer and flash media speeds. It is also used for describing capacities of storage systems including hard drives, DVD and flash storage.
With an aim to get rid of ambiguity in Metric and binary values, IEC developed prefixes that are referred to as kibi, mebi and so forth. Therefore one kibi is equivalent to 1024 bytes and not 1000 bytes as mentioned in Metric system. However IEC made an exception of mentioning kB as 1000 bytes. In spite of this, kilobyte continues to be used to denote 1024 bytes.