What is the difference between streaming and downloading media?

In the digital world, the terms "streaming" and "downloading" have been tossed around for a very long time, "downloading" even longer than "streaming," but what's the difference between the two?

Downloading refers to transferring a file from one device to another, in a very similar way that uploading is transferring a file from one device to another, but in the opposite direction, although sometimes they are acceptably used interchangeably.

Downloading files to CD or DVD and vice versa

Just like if you were copying files from your computer to a CD or DVD, you could realistically call that downloading. And when transferring files from the CD or DVD to the computer's hard drive it could be called uploading. However, both drives being "local", it is more appropriate to just call it "transferring" or "copying."

Downloading from the Internet

On the Internet though, if you purchase a song from iTunes for example, you download it to your computer. Once it arrives on your computer the Internet can be disconnected and you still have access to the file, because you "downloaded" it. You "own" it I guess you could say.

Uploading to the Internet

If you want to add pictures to Facebook that are on a digital camera, in many cases the process would involve transferring (or perhaps uploading) the pictures to the computer. From the computer, those pictures can be "uploaded" to Facebook. Now, there are copies on the camera, the computer and on Facebook.

How is streaming different from downloading?

Streaming is completely different in the fact that no copies are made (although temporary copies can be made, or portions of files can be stored temporarily, but for purposes of explanation, we would say no copies of the files are made).

For example, when watching a video on YouTube, the file is actually being "streamed" to your computer. Streaming allows you to watch the YouTube video without having to download it, and in a lot of cases there are no obvious download options anyway. As is the case with YouTube, the file is usually meant to stay hosted there, and if you intend to watch it again, you must revisit the same page on YouTube and "click play."

One distinction though is that streaming does, in a sense, download bits to the computer. It downloads portions of the file (video, audio, etc.) into a temporary storage area. It downloads ahead of time creating a buffer so that playback is not choppy and does not require you to wait to view. However, this does depend on a few variables such as server and Internet connection speed to work as intended, and stream fluidly with no interruptions.

Can you capture streaming video?

With that said, can you capture streaming video for playback at a later time? In most, if not all cases, the answer is 'yes'. Now, is it illegal to capture streaming data? Depends on the terms of service for what you are streaming in particular, but if there isn't an accompanying download button next to the media, the answer is most likely 'yes' here as well. It is probably against the terms to make attempts at capturing streaming content on the Internet.

Does streaming count as data usage?

Does streaming a video count as downloading in terms of bandwidth usage? It sure does. If you have bandwidth limits, streaming counts towards that number. Now, in some cases, the streamed version might be compressed differently and may send less data then if one were to download the entire file, so in most cases, TCP resend requests aside, the bandwidth used will be the same or slightly less than it would be if downloading the file.

In this article I sort of lumped progressive downloads and streaming together, when in fact they are much different. To explain the difference is out of scope for this article, but one distinction is the protocols used. Progressive download uses HTTP (Hypertext transport protocol) over TCP (Transport control protocol), while streaming may use RTSP (Real time streaming protocol), RTMP (Real time messaging protocol) or MMS (Microsoft media services). True 'live streaming' will use one of the latter three protocols.

Is progressive download the same as downloading?

When referring to a progressive download in most cases large media files are being downloaded. In the case of progressive downloads, you can access the content before it has completely finished downloading, similar to how you can with streaming. Naturally, you can only access the portion that has already been downloaded to the system.

Standard downloading requires that the file has been completely downloaded before it can be accessed or viewed.

The end result of both "types" of downloading is that you have "copied" a file to your computer which takes up permanent storage space (until moved or deleted). The difference with streaming is the file does not stay in permanent storage, it only stays in a temporary storage area until a disconnect from the process is initiated with the communicating protocol.

Streaming video to your home theater

When watching shows via Netflix, for example, you are actually "streaming" the content to a Netflix app. The app communicates with the Netflix servers which authenticates you and makes certain you have an account and are allowed to access the streaming content.

The app can exist on the TV itself, or a set-top box like the Roku, or a device acting like a set-top box, perhaps a mobile smart phone, as is the case when leveraging MHL technology.