Type the command to start the application at the command-line prompt.
application [options] &
application--the application name
options--a list of optional information to be passed to the application
&--indicates that the application runs in the background; that is, you can continue to use the Terminal window while the application is also running
Refer to the man page or other documentation for each application to find the command and options to use for that application.
For example, to start a digital clock from the command line, type:
xclock -digital &