Download particularly refers to data from a server, or other node which is correctly received by another user or computer over the internet from a remote machine. A download in the opposite direction from your computer to another is an upload. "I'm going to download the latest file."
Broadband allows for increased numbers and/or larger files to be transfered. DSL and cable have a download capacity set much higher than the upload. T1 systems, meanwhile have equal download-upload speeds. FTP servers are setup for constant uploads and downloads and file sharing involves both the download and upload of files, creating a copy of the download on a local computer.
2. A file. Usually received after the process mentioned above. (i.e. "send me that download you got.")