The Unity Desktop in Use
As mentioned in the introduction, the main difference you will notice is that applications are now listed in a scrollable bar on the left hand side of the screen (-known as the Launcher) under Unity. Here is an example icon (-for the command line terminal) which is not currently running:

As you launch an application, it's icon appears within this bar (-if it's not already there) and an arrow to the left of the icon denotes that the application is running:

Note: an arrow to the right of the icon denotes that the application is the currently active one (-i.e. the one which receive any input if you were to start typing)
Left-clicking any icon without a window already open (i.e. with no arrow to it's left) will open a new window for that application. Left-clicking any icon with a window already open (i.e. with an arrow to it's left) will make that window the currently active one (-e.g. will unminimize it or bring it to the fore). Left-clicking on the icon for the currently active window will show you a reduced size display of all the currently open windows for that application (-assuming there are more than one):

Just click on the window you desire and that one will assume full size and become the currently active one.
If you wish to access an application whose icon is not yet in the left hand bar, then you will need to left-click the Ubuntu icon (
) in the top left hand corner of the screen and type the name in the search button:
Note: from Ubuntu 12.04 onwards, Canonical moved the Ubuntu Menu into the Unity Launcher itself, as the first icon:


Alternatively (-for example, if you can't remember the name) you can navigate to it using the icons given underneath the search facility (-for example, to look through all internet applications, to find the one you are looking for):

Another change in Unity is that the menu bar for the current (active) application is now displayed at the top of the desktop (-i.e. the top line of the screen) rather than the top line of the application window itself:

This is apparently to save space - albeit at the expense of having to move the mouse up and down between the top of the screen and the active window, which can be a little wearing. Note that the LibreOffice suite was an exception to this rule (-i.e. it's menu bar is anchored to the active window) up until Ubuntu 11.x -and you may well come across other non-conformant applications.
When using Unity, there are many keyboard shortcuts you can use to save yourself time. The full set can be viewed by holding down the Super (-aka the Option or Windows) key:

Here are some of the most useful:
| Shortcut | Area | Usage |
|---|
| Super (hold) | Help | List the most common keyboard shortcuts (-see above) |
| Super + W | Windows | Display an overlay of thumbnails of all open windows |
| CTRL + Super + D | Windows | Minimize all open windows |
| CTRL + Super + Up Arrow | Windows | Maximize the current window |
| CTRL + Super + Down Arrow | Windows | Restore the current window size |
| CTRL + Super + Left Arrow | Windows | Size the current window to fit the left half of the screen |
| CTRL + Super + Right Arrow | Windows | Size the current window to fit the right half of the screen |
| Super + Tab | Applications | Scroll through the Launcher icons and run/activate the selected application |
| Alt + Tab | Applications | Switch between open applications |
| Alt + Tab + ` | Applications | Switch between open applications using a preview window |
| Super + S | Workpaces | Display the workspace switcher |
| CTRL + Alt + Arrow Key | Workpaces | Switch to a different workspace |
| Super (tap) | Dashboard | Opens the Dash home |
| Super + A | Dashboard | Search for applications |
| Super + F | Dashboard | Search for files |
| Super + M | Dashboard | Search for music |
| Super + V | Dashboard | Search for videos |