"Uploading" and "downloading" are terms used to refer to types of electronic data transfers. The difference between them is the direction in which the files are being transferred. Files are considered to be uploaded when they are transferred from a computer or other electronic device to a central server, and downloading is when the files are transferred from a server to a smaller peripheral unit, such as a computer, smartphone or other device. These two different types of transfers are often done via the Internet, such as when a file is downloaded from a website. The transfer of data from one system or device to a similar system or device, such as from a desktop computer to a laptop, usually is not considered uploading or downloading.
The most common type of uploading is when a user uploads a digital file to an Internet site. For example, a user might upload vacation photos to a social networking website or a home video to a video sharing site. The uploaded files are then stored on the website's servers and can be seen by anyone who has Internet access and, if necessary, the right software for viewing it.
Other websites allow users to upload digital files for storage. This can allow users to store more files or larger files than would be possible to store on their own computer or device because of its limited storage capacity. Uploading files to storage websites also allows other users or other devices to have access to them. Permission to access the files can be granted to only certain people, or the files could be made public for anyone to access.
Another type of uploading takes place within a closed computer system, such as one within a single office building or one that connects a group of businesses. These types of systems typically have servers to store information that needs to be shared among multiple computers or devices. Digital files can be uploaded from any computer or device that is connected to the system, then can be downloaded or accessed by any other user in the system.
Whenever electronic files or information are transferred from a central system to a computer or device that is connected to that system, it is considered downloading. Files can be downloaded temporarily and then deleted after they have been used once, or they can be downloaded on a more permanent basis and used for a long period of time. For example, a funny video file might be downloaded from the Internet and soon deleted after it has been watched, but a helpful application might be downloaded and used for months or years.
Downloaded files are sometimes automatically stored in a particular location on the computer or device, and they are automatically accessed from that location when needed. An example of this is an application that is downloaded to a smartphone — the user typically cannot control where the app is stored on the phone, it is simply stored where the phone stores all of its apps. In other cases, the user can choose where the downloaded files will be stored. For example, a laptop user might download a music file to a specific folder for music or another type of file to the computer's desktop, where it can be found quickly.
The time that it takes to upload or download a file depends on several factors. The main factor is the digital size of the file, which is measured in bytes. The larger the file, the longer it takes to transfer the information in it.
The quality of the connection from the Internet or central server to the smaller computer or device also makes a difference in the transfer speed. A computer that has high-speed Internet connection will be able to download or upload a file much more quickly than a computer that has a low-speed connection would. In addition, the speed of the server on which the file is stored can affect upload times or download times.
Uploading and downloading occur frequently, often without the user being aware that he or she is doing it. For example, incoming email is downloaded from a server, and outgoing emails are uploaded to be sent out. The source code of a web page is downloaded to the user’s computer so that he or she can view the content. Whenever a computer or device is connected to the Internet or another larger system, files are frequently transferred back and forth — uploaded and downloaded — throughout the normal course of use.