What is the reasoning of Crtl, shift, and Alt when using tools?

[elindo586]

Using the Shape Builder tool it combines shapes if you press shift, but it deletes shapes if you press Alt.

Is there any secuence or reasoning on how a tool is going to behave giving the options of CTRL, SHIFT, and ALT?

[Monika Gause]

Shift usually makes somewhat even shapes or adds selections.

Alt toggles alternative behaviours of tools.

Ctrl on Windows (Cmd on Mac) switches to a selection tool as long as you hold that key.

Cmd on Mac opens the contextual menu