How does YouTube work?

Since it first launched in 2005, YouTube has quickly become the number one destination for video content online, attracting over one billion regular users. The Google-owned site gained popularity by enabling people to share their videos with others all over the world, whether it’s an amusing clip of their pet, or footage of them dancing in their living room.

It’s not all about cute cat videos and funny home movies though, as YouTube has also helped people launch careers. For example, pop star Justin Bieber was first discovered when a talent scout saw videos of him singing on the site, and Zoe Sugg, aka Zoella, has got her own book deal and range of beauty products as a result of her popular video blog, or ‘vlog’. You can even earn money directly from YouTube too, as the site shares some of the revenue it makes from companies who pay to run adverts before or over your video.

The popularity of YouTube is mainly down to how easy the website is to use. Videos in a range of file formats can be uploaded as YouTube converts it into its Adobe Flash video format, with the file extension .FLV, for you. This enables the video to be played using YouTube’s Flash player, which can be installed on your computer or smart device for free.

Another benefit of YouTube is the ability to embed videos on other websites. By simply copying and pasting a bit of HTML code, you can enable people to watch a video on your own website using the YouTube player. This saves you having to host the video on your site which requires a lot of bandwidth. Bandwidth is the range of signal frequencies needed to transmit data over the internet and you have to pay for the amount you use. YouTube streams vast amounts of data each day, carrying the bandwidth burden for other sites that want to display video.

Although embedding is great for spreading your videos further across the internet, most people will actually find them simply by searching. To help connect users to the videos they are looking for, YouTube uses a complex algorithm made up of over one million lines of code. When you search for a video, the algorithm decides which search results it will show you and in what order. One of the main factors used to rank the results is video metadata. This is the title, description, thumbnail and tags that you give your video when you upload it, so you should make sure they are relevant to the content of the video and what people might search for to find it. However, the other ranking methods YouTube uses are out of your control. The site used to rank its videos by how many times they had been viewed, but this presented a few problems. It often meant that new videos were pushed to the bottom of the list as their view counts had not yet had a chance to grow, and it also enabled people to manipulate their ranking by clicking on their video repeatedly, as clicking the play icon counts as a view.

To combat these problems, YouTube has switched to a new system of measuring a video’s quality by the length of time it has been watched for. If several users have stopped watching after a few seconds, this suggests that the video had a misleading title or thumbnail and didn’t give viewers what they were looking for, whereas if they stayed to watch until the end it was most likely appropriate for the search terms used and therefore worthy of a high ranking. The rest of YouTube’s ranking tricks are a mystery though, as the company is very secretive about its algorithm and changes it all the time to stop people manipulating it.

Video storage

Every video uploaded to YouTube is stored in at least one of Google’s 14 data centres spread across the world. These enormous buildings contain thousands of servers – the powerful computers that handle the billions of Google searches made every day and also store your videos. Giant cooling towers keep the temperature inside at a steady 27 degrees Celsius (80 degrees Fahrenheit) to ensure the equipment runs smoothly, and each piece of data is stored on at least two servers for extra security. The data centres can also communicate with each other to send information between them. When you upload your video it will be stored at the data centre nearest you, but when someone wants to play it, the video will be sent to their nearest data centre for quick access. This also means that in the event of a fire or other disaster, the data is sent to another data centre so that it’s always accessible.

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