What is a byte?

We use units of meas­ure­ment to make sense of our everyday lives. A day is 24 hours long, or 1,440 minutes, or 86,4000 seconds. We weigh ourselves in stones and pounds. Liquids are measured in mil­li­litres and litres, and distances are measured in miles. Another unit of meas­ure­ment that affects our daily life is the byte. Bytes are used to express how many photos you can store on your phone or when it’s time to clean out your computer’s hard drive. They’re the smallest unit of meas­ure­ment for quant­it­ies of data. Let’s take a closer look at what bytes are all about.

If you want to truly un­der­stand the byte, you’ll have to first fa­mil­i­ar­ise yourself with the bit. Whereas bytes are the smallest quantity of data, bits are the building blocks that bytes are made up of. The name ‘bit’ comes from binary in­form­a­tion digit. The term was used for the first time by math­em­atician John W. Turkey and then pop­ular­ised by tech­no­logy pioneer Claude E. Shannon in his 1948 treatise ‘A Math­em­at­ic­al Theory of Com­mu­nic­a­tion’. Shannon is thus con­sidered the ‘father of the bit’.

The bit is the smallest unit of in­form­a­tion in digital com­mu­nic­a­tions - it can represent just one of two states, 1 or 0. Since computers only know two states and com­mu­nic­ate in binary code, the bit is the smallest dis­tinc­tion that a computer can un­der­stand and address.

1 bit = 1 or 0 (‘On/true’ or ‘Off/false’)

Bits them­selves are too small to represent, for example, a letter. Even so-called ‘nibbles’, which are composed of 4 bits, are too small to be of use. Bytes are the dominant unit of meas­ure­ment for cal­cu­lat­ing quant­it­ies of data or storage ca­pa­cit­ies. It was IBM engineer Werner Buchholz who developed the term ‘byte’ from ‘bit’, in order to clearly dis­tin­guish between the smallest quantity of data and the smallest unit of in­form­a­tion.

A byte consists of 8 bits and is often ab­bre­vi­ated with ‘B’. Unlike the bit, which can only represent one of two states, the byte can represent 256 (2⁸) states.

1 byte = 8 bits = 2⁸ = 256 values

A byte could look as follows: 00111001.

Since each bit in a byte can be either a 1 or 0, there are 8 different places for a 1 to appear:

00000001

00000010

00000100

00001000

00010000

00100000

01000000

10000000

If you imagine the bit as a binary letter, then a byte is the smallest possible word. It takes 1 byte to represent an actual letter or number.

Why are bits per second (bps) used when talking about internet speeds, while mega-, kilo-, or terabytes are used for storage sizes? The answer is simple - bits describe speed and the amount of data used with the bitrate. Bits can show how many units of data have been trans­ferred in a specific period of time.

Bytes are the unit of meas­ure­ment for storage sizes and storage ca­pa­cit­ies. A digitally active person generates between 700 megabytes and 1 gigabyte a day in downloads and uploads. 1 gigabyte (GB) converts to 1 billion bytes. In 2020, 59 zetta­bytes of data were generated worldwide. 1 zettabyte cor­res­ponds to 1 sex­til­lion bytes (10²¹) - that is, di­men­sions that can barely be com­pre­hen­ded.

We produce more and more data every year and need more storage space. So, it comes as no surprise that the first hard drives gave their storage capacity in megabytes, then switched to gigabytes in 1997, and now use terabytes.

The byte is too small to express large quant­it­ies of data. That’s where ex­po­nen­tial powers come in. There are two different prefix systems that are used to express byte quant­it­ies: binary prefixes and decimal prefixes.

Since computers com­mu­nic­ate in binary, binary prefixes are the more precise system. They indicate the exact quantity of data and thus provide a more accurate rep­res­ent­a­tion of storage ca­pa­cit­ies. However, despite the re­com­mend­a­tion of the In­ter­na­tion­al Elec­tron­ic Com­mis­sion (IEC), binary prefixes haven’t gained much traction. Decimal prefixes are widely favoured, even though they indicate less precise, rounded data quant­it­ies.

Currently there are the following eight standard labels with decimal prefixes:

To indicate quant­it­ies of data and storage sizes more precisely, you can use the following binary prefixes:

Mega-, giga-, and terabytes are abstract sizes. When it comes to zetta- or yot­ta­bytes, the di­men­sions are beyond our ima­gin­a­tions. Some practical examples from daily life can help to make these sizes more com­pre­hend­ible:

1 byte = 1 letter/character

1 megabyte = 1 book (with 200 pages)

1 gigabyte = around 595 photos

1 terabyte = around 250,000 photos, 250 movies, and 500 hours of HD video

1 petabyte = around 15 trillion photos on Facebook

1 exabyte = 320 trillion copies of the Bible

1 zettabyte = all the traffic on the Internet in 2016

1 yottabyte = all of the atoms in 7,000 human bodies