Glossary:

Upload

To upload or uploading is the process of transmitting a file from a client computer to a server.

Typically this refers to transmitting a file or data from your home or work computer to a remote destination via the Internet.

Upload corresponds to sending information, the opposite of which is to download.

Most internet connections have a larger bandwidth for downloading as compared to uploading.  This is because the majority of internet users spend more time viewing information (downloading) than sending information (uploading).