There are times when you want to execute an application on the command-line without interrupting the most recent process or application that is running. Whilst this is very basic, I find that n00bs may not be familiar with this trick.
On the command-line, execute a process, e.g., "ping" without the trailing "&" that keeps it running in the background. Hit Ctrl-Z to temporarily stop the process.
Activate it but run as a background process.
Continue doing what you are doing but the process continues to run in the background.
Transfer it back as the current process.
Now, the process is back as the currently running application.