It can be easy to confuse the terms download and upload. While downloading and uploading both involve moving data between computers over a network, the difference is in direction.
Up vs. down
Downloading is copying data to your computer from another computer, usually a server. Servers are computers you connect to via the internet that host websites, files, and other data. Even basic tasks, such as visiting a website, checking your email, or watching a YouTube video, involve downloading.
Uploading, on the other hand, is when you copy data from your computer to a server. Common forms of uploading include attaching files to emails, posting pictures on social media, or using video chat services like Skype. (Video chat is actually an example of both uploading and downloading at the same time, since you’re sending and receiving video simultaneously.)
A matter of speed
Downloading and uploading are also relevant when it comes to paying for internet service. Your internet connection is measured in megabits per second (Mbps). Basically, this is a measurement of how much data you can transfer at any given time, which is also known as bandwidth.
Most internet service providers (ISPs) provide more bandwidth for downloading than they do for uploading. This is because most internet traffic in the average household takes the form of downloading data (browsing the web, streaming videos, etc.) rather than uploading.
The difference between these two speeds is often significant—for example, your download speed might be 15 Mbps while your upload speed is limited to only 1 Mbps. In cases like this, you’ll find that it’s quicker to download a file than it is to upload a file of the same size.
To test your download and upload speeds at home, go to http://www.speedtest.net/ and click Begin test.