How To Enable And Disable Startup Applications in Ubuntu 12.04 Precise Pangolin

Many newly installed and pre-installed applications start up with the Ubuntu operating system. This contributes to the amount  of time required for the operating system to fully load and also results in the annoyance of having to manually close programs when the system starts. For example, a program may register itself to start at system start-up and an app-indicator menu applet may initiate each time the OS boots.