Internet Streaming: What It Is and How It Works

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Streaming is a technology used to deliver content to computers and mobile devices over the internet. Streaming transmits data—usually audio and video, but increasingly other kinds as well—as a continuous flow, which allows the recipients to begin to watch or listen almost immediately without having to wait for a download to complete.

Two Kinds of Downloads

Illustration of a person in an office chair spinning around and listening to music on their laptop
Lifewire / Miguel Co

The internet has two main ways to view media: streaming and progressive downloads. Streaming is the quickest means of accessing internet-based content, but it's not the only method. Progressive download is another option that was around for years before streaming was possible. The key differences between the two are when you can start watching and what happens to the content after you view it. 

Progressive downloads are the traditional kind of download that anyone who's used the internet is familiar with. When you download an app or game or buy music from the iTunes Store, you need to download the entire thing before you can use it. That's a progressive download. 

Streaming lets you start using the content before the entire file downloads. When you play a song on Apple Music or Spotify, you can click Play and start listening almost immediately. You don't have to wait for the song to download before the music starts. This is one of the major advantages of streaming: It delivers data to you as you need it. 

The other major difference between streaming and downloads is what happens to the data after you use it. For downloads, the item stays on your device until you delete it. For streams, your device automatically deletes the data after you use it. A song you stream from Spotify isn't saved to your computer (unless you save it for offline listening, which is a kind of download).

Requirements for Streaming Content

Streaming requires a relatively fast internet connection; just how fast depends on the type of media you are streaming. A speed of 2 megabits per second (Mbps) or more is necessary for streaming standard-definition video without skips, reductions in quality, or buffering delays. HD and 4K content require higher speeds for flawless delivery: at least 5 Mbps for HD content and 9 Mbps for 4K content.

Live Streaming

Live streaming is the same as the streaming discussed above, but it's specifically used for internet content delivered in real-time as it happens. Live streaming is popular with live television shows, gaming broadcasts, and special one-time events or sports.

Streaming Games and Apps

Streaming has traditionally delivered audio and video, but Apple has recently implemented technology that allows streaming to work with games and apps, too.

This technique, called on-demand resources, structures games and apps to include a core set of functions when the user first downloads them and then streams new content as the user needs it. For example, a game might include its first four levels in the initial download and then automatically download levels five and six when you start playing level four.

This approach is useful because it means downloads are quicker and use less data, which is especially important if you have a data limit on your phone plan. It also means that apps take up less space on the device they're installed on.

Problems With Streaming

Because streaming delivers data as you need it, slow or interrupted internet connections can cause problems. For example, if you have streamed only the first 30 seconds of a song, and your internet connection drops before any more of the song has loaded on your device, the song stops playing.

The most common streaming error that crops up has to do with buffering. The buffer is a program's temporary memory that stores the streamed content. The buffer is always filling up with the content you need next. For example, if you watch a movie, the buffer stores the next few minutes of video while you're watching the current content. If your internet connection is slow, the buffer won't fill up quickly enough, and the stream either stops or the quality of the audio or video decreases to compensate.