Measurement Terminology

Size (Memory Storage)
Name	Symbol	Meaning	Value
Bit	b	One binary digit	0 or 1
Byte	B	8 bits	1 Byte
Kilobyte	kB	Thousand Bytes	1 × 103 Bytes
Megabyte	MB	Million Bytes	1 × 106  Bytes
Gigabyte	GB	Billion Bytes	1 × 109  Bytes
Terabyte	TB	Trillion Bytes	1 × 1012 Bytes
Petabyte	PB	Quadrillion Bytes	1 × 1015 Bytes
Exabyte	EB	Quintillion Bytes	1 × 1018 Bytes
Zettabyte	ZB	Sextillion Bytes	1 × 1021 Bytes
Yottabyte	YB	Septillion Bytes	1 × 1024 Bytes
Speed
Name	Symbol	Meaning	Value
Hertz	Hz	1 pulse per second	1 Hz
Millihertz	mHz	Thousandth of a second	1 × 10-3 Hz
Microhertz	mHz	Millionth of a second	1 × 10-6 Hz
Nanohertz	nHz	Billionth of a second	1 × 10-9 Hz
Picohertz	pHz	Trillionth of a second	1 × 10-12 Hz
Femtohertz	fHz	Quadrillionth of a second	1 × 10-15 Hz
Attohertz	aHz	Quintillionth of a second	1 × 10-18 Hz
Zeptohertz	zHz	Sextillionth of a second	1 × 10-21 Hz
Yoctohertz	yHz	Septillionth of a second	1 × 10-24 Hz
·      Processor speed is measured in MHz (1MHz = 1 × 106 Hz)  or GHz (1GHz = 1 × 109Hz) ·      Clock speed is measured in MHz (1MHz = 1 × 106 Hz)  or GHz (1GHz = 1 × 109Hz) ·      Hard disk drive speed is measured in mHz (1mHz = 1 × 10-3 Hz)   ·      Main memory speed is measured in mHz (1mHz = 1 × 10-6 Hz) ·      Circuit speed is measured in nHz (1nHz = 1 × 10-9 Hz)