2.3.1 The mouse 
Blender is designed as a two-handed system. To minimize mouse strain, almost all commands are available as mouse buttons as well as keyboard hot keys. There's a Toolbox command (press spacebar) that lists - and can activate! - the hot keys. As a finishing touch, some commands are available as gestures. 

As far as possible, the usage of the mouse has been standardized:  

LeftMouse: for buttons, sliders, text input, placing a cursor. 
LeftMouse+CTRL: add a vertex. 

MiddleMouse: to change the view or - during actions - the delimiter. 
MiddleMouse+Shift: change view 
MiddleMouse+Ctrl: zoom in/out view 

RightMouse: selecting  
RightMouse+Shift: extend select. 
RightMouse+CTRL: selecting, only at Object centers. 
RightMouse: select-hold-move-release: translation mode. 

2.3.2. The Keyboard 
For the keyboard, these are the common rules: 
F1 - F12: global hot keys, independent of window type. 
ESC: to restore or escape from anything (menu's, editing, rendering, file selecting, ...)  
Numerical Pad (NumPad): view related hot keys. 
Spacebar: Toolbox menu. 

2.3.3 Selecting 
Selecting with a RightMouse click ALWAYS selects only 1 item, it deselects everything else (for this Scene and active layers). Holding SHIFT while selecting, selects or deselects the indicated item only.  
Besides using the mouse, items can be selected with a 'border': press 'b'. Draw a border with LeftMouse to select, RightMouse to deselect.  
Another important selecting option is the a-key. Pressing 'a' selects ALL or deselects all.  

2.3.4 Active Data 
There is an important distinction between SELECTED and ACTIVE in Blender. Several Objects (or vertices, faces, whatever) can be SELECTED, only 1 of them can be ACTIVE. The rule is: the last item selected/deselected with RightMouse is always ACTIVE. Objects in wireframe display this in a slightly different color.  
This is important because of the non blocking interface of Blender. Most hot key actions perform at all SELECTED data. But the Button and Animation Curve windows can only display the contents of ACTIVE data.  
This implies that the user can set up a screen with (for example) a material editor and a window with transformation curves. One single RightMouse click on an Object immediately updates the current settings in all windows.  
Working with Blender windows is parallel, non blocking and directly connected to the visualized data. 

2.3.5. Moving / rotating / scaling 
These basic commands are implemented as subroutine modes.  
Independent which window or item, for selected data the hot keys are: 
G: grab/move/translate. 
R: rotate 
S: scale 
The selected items now move with a mouse movement or with the (keyboard) arrow keys.  
Press LeftMouse or Space to leave the mode. Pressing ESC or RightMouse leaves the mode without changes. 

Pressing RightMouse-select-hold-move-release also starts translation mode. In this way, selecting and grabbing is combined. Useful to quickly move Objects or move vertices and Bezier handles.  

Gestures: 
Draw with LeftMouse a straight line: starts translation mode. 
Draw with LeftMouse a curved line: starts rotation mode. 
Draw with LeftMouse a V-shaped line: starts scaling mode. 

2.3.6. Objects and edit mode 
If you select Objects, all 3D editing is done at the abstract Object itself. You can't change the number of faces or translate some of the vertices. 
To work at the Object Data, (the Mesh, Curve, Text, Surface..) you have to enter EDIT MODE. This can be done in 3 ways: 
- TAB 
- Alt-e 
- press the small triangle button in the 3D window header. 
Now editing is locked to this single data block of the ACTIVE Object. All actions perform at the lowest level. Add vertices, add faces or type text. Extrude, draw curves, assign colors. You can't activate other Objects or another Scene. For this you have to leave edited by pressing TAB, Alt-e, or the edit mode button again. 
While entering edit mode, Blender makes a copy of the indicated data. The hot key 'u' serves as an undo function: "reload original data". 
To remind being in edit mode, the cursor shape changes to a cross. 

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