Desktop Shortcuts

Activate menu bar - Alt
File menu - Alt+F
Edit Menu - Alt+E
View Menu - Alt+V
Undo - Ctrl+Z
Redo - Ctrl+Y
Cut-Ctrl+X or Shift+Del
Copy - Ctrl+C or Ctrl+Ins
Paste - Ctrl+V or Shift + Ins
Paste special - Ctrl+Alt+V
Select All - Ctrl+A
Toggle between installed keyboard languages - Shift+Alt

Windows system key combinations

F1: Help
CTRL+ESC: Open Start menu
ALT+TAB: Switch between open programs
ALT+F4: Quit program
SHIFT+DELETE: Delete item permanently
Windows Logo+L: Lock the computer (without using CTRL+ALT+DELETE)

How optical mice works ?

Developed by Agilent Technologies and introduced to the world in late 1999, the optical mouse actually uses a tiny camera to take 1,500 pictures every second.
Able to work on almost any surface, the mouse has a small, red light-emitting diode (LED) that bounces light off that surface onto a complimentary metal-oxide semiconductor (CMOS) sensor. The CMOS sensor sends each image to a digital signal processor (DSP) for analysis. The DSP, operating at 18 MIPS (million instructions per second), is able to detect patterns in the images and see how those patterns have moved since the previous image.
Based on the change in patterns over a sequence of images, the DSP determines how far the mouse has moved and sends the corresponding coordinates to the computer.
The computer moves the cursor on the screen based on the coordinates received from the mouse. This happens hundreds of times each second, making the cursor appear to move very smoothly.