How to Select Objects in Blender
How you select objects is one of the most controversial design decisions in Blender’s interface: In nearly every other program, you select things — be they text, 3D objects, files, or whatever — by left-clicking them. This is not the case in Blender. When you left-click in the 3D View, all it seems to do is move around some strange crosshair thing. That “thing” is Blender’s 3D cursor.
The answer is simple: You select objects in Blender by right-clicking them. Multiple objects are selected and deselected by Shift+right-clicking them.
Although right-clicking to select certainly seems strange, there is actually a reason for doing it this way. This design decision wasn’t made at random or just to be different for the sake of being different. There are actually two reasons for doing it this way. One is philosophical, and the other is practical.
Separating selection from action: In Blender, the left mouse button is intended to be used to perform or confirm an action. You left-click buttons or menus and left-click to confirm the completion of an operation like moving, rotating, or scaling an object, and you use it to place the 3D cursor. Selecting an object doesn’t really act upon it or change it.
So right-click is used to select objects as well as cancel an operation before it’s completed. This setup is a bit abstract, but as you work this way, it does actually begin to make sense. A functional example would be interacting with the 3D manipulator. If action and selection are on the same mouse button, it becomes too easy to accidentally move an object using the 3D manipulator when you only meant to select, and vice versa.
Prevention of Repetitive Stress Injury (RSI): Computer graphics artists like 3D modelers and animators are known for working at a computer for insanely long stretches of time. Repetitive stress injury, or RSI, is a real concern. The more you can spread the work across the hand, the lower the chance of RSI. By making it so that you’re not doing every single operation with the left mouse button, Blender helps in this regard.
Bottom line, the right-click-to-select paradigm really is a nice, efficient way of working in 3D space after you get used to it. However, if you try it and still don’t like it, Blender offers you the ability to swap left and right mouse button usage in the Input section of User Preferences. Do note, however, that this book is written with the default right-click behavior in mind, so remember that as you read other chapters.