Broadband is an essential part of modern life, and upload and download speeds are central to any online experience.

High speeds will ensure a smooth and seamless journey around the web, while slow speeds generally lead to frustration.

Understanding how data is transmitted across the internet helps to explain why your current connection sometimes struggles to keep up, and whether an advertised line speed would deliver a better service.

Getting the bit between your teeth

Any internet connection involves distributing the smallest piece of data a computer can understand – a bit.

This is simply an instruction that something should be on or off – 1 or 0 – and it’s known as binary because there are only two options.

This simple binary data fragment is repeated millions of times to enable electronic devices to function, and to generate content which is displayed and interacted with.

Every webpage you visit or design, every online gaming experience, every Zoom chat with colleagues and relatives – they’re all comprised of countless individual bits.

Byte down

At this point, there’s a key distinction to be made. Bits tend to be packaged together into bundles of eight, known as bytes.

Bytes are the unit of measurement for data size – a JPG picture on your phone might be five megabytes, or roughly 5,000 bytes.

Similarly, storage devices are measured in gigabytes or terabytes, abbreviated to capital letters depending on whether they’re megabytes (MB), gigabytes (GB), and so forth.

While bytes are the chosen unit of measurement for size, bits are the chosen unit for speed. Internet connections have always been measured in bits, which are written in lowercase and recorded per second.

You might remember dial-up internet connections and the modems used to go online promising speeds of up to 56Kbps – that’s 56 kilobits (thousand bits) per second.

As broad’ as it’s long

Of course, nobody uses dial-up internet any longer. We’ve all moved on to broadband, with speeds measured in megabits per second (Mbps). In other words, rather than thousands of bits being sent and received by our internet-enabled devices every second, there are millions of them.

This has allowed the development of modern services such as streaming media platforms like Netflix, and software packages hosted remotely rather than being installed onto a computer.

Now we know how internet traffic speeds are measured, it’s important to consider the difference between uploads and downloads:

  • Uploads: information sent from a device to a central server.
  • Downloads: information sent from a central server to a device.

There is a constant two-way dialogue going on between connected devices and the internet. For example, your actions during online gaming are being fed back to the host servers in real time, enabling them to interpret these commands and ensure the game responds accordingly.

The only occasions when traffic tends to be purely one-way is when you’re doing something specific like transferring a document to or from a cloud server like Dropbox.

Down on the upside

Although you may spend quite a bit of time creating webpages and moving media files online (both examples of uploading), most internet traffic to computers/tablets/smartphones is downloaded.

As such, internet service providers tend to bias broadband connections in favour of downloads. The most recent data from Ofcom suggests the average download speed is over four and a half times faster than the average upload speed.

Many domestic connections are biased 10:1, meaning a file would download ten times faster than it could be uploaded as an email attachment, for instance.

The vast majority of information downloaded via the internet comes from dedicated data servers, which are specifically designed to transmit information as quickly as possible along fibre connections.

By contrast, people tend to consume far more than they create, so the bias in connection speeds makes sense – though it’s frustrating if you suddenly have to upload a large volume of data.

How fast can my connection go?

This depends on the connections used to transmit data to and from a device. Many of the UK’s telephone line connections are limited to 11Mbps, whereas fibre-optic cabling (commonly referred to as full fibre) is far more efficient at delivering super-fast data into your home or workplace.

Because fibre cabling can transmit individual bits of data almost as fast as the speed of light, these connections can maintain average download speeds of 1Gbps – a thousand megabytes per second.

The UK Government has set a target of giving every home gigabit connectivity by 2025, but this would require enormous investment in fibre-optic cable infrastructure.

If you want to check your current internet connection speed, there are plenty of websites which conduct live testing to see how quickly uploading and downloading is taking place. Popular examples include Broadband Speed Checker, or the testing utility produced by consumer body Which?.

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