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By Jose Manuel Enriquez Mora

How many Megabytes (MB) does a file weight? How many Gigabytes (GB), or Terabytes (TB), does the hard drive of a new computer have? How much memory do I need to store 1,000 pictures or a movie? All these words of digital measurement are already part of our everyday language, although few of us really know exactly what they mean nor understand their magnitude.

All the digital information in the world—be it a phone call, an email, a WhatsApp message, a YouTube video, and even this article you are reading— is reduced to the binary system; that is, to a series of 0’s and 1’s.

**Bits (b)**

The most basic unit of the binary system is a bit, a bit can be a 0, or a 1. In fiber optic communication systems, a 1 is a pulse of light (or ON), while a 0 is nothing (or OFF).

**Bytes (B)**

A bit by itself does not mean anything, for it to make sense, it must be grouped with other bits into units of digital information called bytes. Historically, a byte is the minimum number of bits required to store a letter in a computer. In the 60s it was common to see systems that used bytes of 6 or 9 bits, so it was common to see words of 12, 18, 24, 30, 36, 48 and 60 bits, corresponding to 2, 3, 4, 5, 6, 8 and 10 “6-bit” bytes. Currently, the de facto standard is that a byte consists of 8 bits (also known as an octet). For example, the letter A of the alphabet would be a byte with the following code: 01000001; however, there are more complex characters—like emojis—that require 4 bytes to represent them.

**Data Measurements**

Strictly speaking in binary system, a byte would be 2^{0}, a Kilobyte (KB) would be 2^{10} (that is 2x2x2x2x2x2x2x2x2x2) = 1024 bytes, 1 MB = 2^{20} or 1024 MB, 1 GB = 2^{30 }or 1024 MB, etc. For practical purposes, today it is accepted to use the rounded-up equivalent in decimal; when we talk about memory or storage capacity, one KB means 1,000 Bytes, 1 MB = 1,000 KB, 1 GB = 1,000 MB, etc.

**Speed measures vs storage measures**

Let us not confuse storage measurements with Internet speed measurements. Most Internet providers advertise their Internet speed in MEGAS, and many people assume them to be Megabytes per second (MB/s), when in reality they are Megabits per second (Mbps or Mb/s). To find its equivalent in Megabytes per second, just divide by 8, so a speed of 100 Megas (Mbps) is equal to 12.5 Megabytes per second (MBps).

**How big is a GB vs a TB, a PB, a ZB and a YB?**

It is difficult to visualize such abstract measurements made up of zeros and ones. In metric length measurements, for example, it is quite easy to visualize the difference in magnitude between a mm, a cm, a meter, and a km; however, in the binary system, it is more complex to understand the magnitude of its measurements. To help us visualize this, let us look at the following data size examples:

An average email has 30 KB, a picture, or a song measures between 4-5 MB, a movie—depending on its quality—is between 1.5 and 4 GB, and 6 million books are equivalent to 1 TB. If we were to store all the information equivalent to a PB on DVDs, there would be enough DVDs to form a 55-story building (225 meters tall), like Torre Mayor in Mexico City. It is estimated that the global traffic in 2020 was around 59 ZB and IDC estimates that by 2025 the amount of data created and stored throughout the planet will be around 175 ZB. To put such an abstract number into perspective, IDC gives us the following visual aids:

- If you were to store 175 ZB on DVDs, the stack of DVDs would be so long that it would get you to the moon 23 times or circle the earth 222 times!
- Or, if a person wanted to download 175 ZB of information at the speed of 25 Mbps, it would take 1800 million years; even if we enlisted the entire population of the planet to help, it would take 81 days to download such amount of data.

We live in a data-hungry world that every day consumes and generates more data exponentially. So much data that, to store it and transmit it, the world requires increasingly larger data centers, as well as more and better fiber optic infrastructure systems that will be able to carry all this traffic.