Learn about Ubuntu Software Center
You can use "Ubuntu Software Center" to know all the installed applications and available applications to install in Ubuntu.
To open Ubuntu Software Center, follow the below steps,
Step 1: Type as "software" in the search box.
Step 2:Click "Ubuntu Software Center" icon from the search results.
Step 3: "Ubuntu Software Center" window opens and list the available applications.
Note: You need root password to install an application using the ubuntu software center.