The following shortcuts can be used throughout Windows and Linux applications to enhance your productivity (I can see some people still didn't adopt those):


Ctrl+C - Copy
Ctrl+V - Paste
Ctrl+X - Cut
Ctrl+Z - Undo
Ctrl+Y - Redo
Ctrl+A - Select All
Ctrl+N - New document
Ctrl+S - Save document
Ctrl+O - Open document
Ctrl+F - Find text
Ctrl+P - Print
Alt + First letter in menu item (sometimes other letter) - Open menu (i.e. Alt+F opens the File menu)
Ctrl+Tab - Switch between open documents
Ctrl+F4 - Close document

Alt+F4 - Close active application
Alt+Tab - Switch between open applications
Alt+Shift (Default, but can be changed in keyboard settings) - Switch between installed keyboard input languages
Alt+Print Screen - Copy only the contens of active window to clipboard

The following apply to various text editors:

Ctrl+H - Replace text
Ctrl+Home / Ctrl+End - Go to the beginning/end of document (can be used in combination with Shift for selecting)
Ctrl+Left Arrow / Ctrl+Right Arrow - Move to next word left/right (can be used in combination with Shift for selecting)

Windows 7 or higher specific

Win+X - Quick menu
Win+Up Arrow - Maximize window
Win+Down Arrow - Un-maximize or minimize window
Win+Tab - List view of all open apps
Alt+Shift+Print Screen - Switch between High Contrast and Normal modes
Win+R - Run a command
Win+G - Game Bar - Start recording a video of your game or some apps that allow recording

Zooming in/out in browsers and text editors

Internet browsers support both:
Ctrl + Mouse wheel up/down
and
Ctrl + +(NumPad) / Ctrl + -(NumPad),
but some text editors only support the mouse method, others support none.


I know there's more, but I find these to be the most relevant...