These are the Most Popular Keyboard Shortcuts for Firefox :

Ctrl+N - It use for Open New Browser Window.

Ctrl+T - It use for Open New Tab on Existing window.

Ctrl+W or Ctrl+F4 - It use for Close the current window or Tab.

Ctrl+R or F5 - For refresh The Page

Ctrl+F5 orCtrl+Shift+R - Refresh the page with override cache

Esc - Stop

Ctrl + O - It use for Open File

Alt+Home - Home

F1 - Firefox Help

F11 - Toggle Full Screen of Browser Window.

Ctrl+Tab - For Changing Tab between Existing window.

Ctrl+U - Open View Source Page of any webpage.

Ctrl+I or Ctrl+B - Open Bookmark window in left sidebar

Ctrl+P - For Print Command

Ctrl+A - Select All

Ctrl+S - Save Page As

Ctrl+D - Bookmark This Page

Ctrl+F - Find

Ctrl+G or F3 - Find Again

Ctrl+H - open History Window In left Sidebar.

Ctrl+J - Open Downloads Window

Ctrl+Z - Undo Your Process

Ctrl + Y or Ctrl + Shift + Z - Redo your Process

Ctrl+C - Copy

Ctrl+V - Paste

Ctrl + Shift + Delete - Clear your Private Data

F7 - To Open Browser in Caret mode

Backspace or Alt+Left Arrow - Back

Shift+Backspace or Alt+Right Arrow - Forward

Alt + Enter - Copy your existing window tab and Open It in New Tab

Ctrl + Tab or Ctrl + Shift + Tab — rotate forward to the next window tab

Down Arrow – Scroll down

Ctrl+ "+" or Ctrl+ Scroll up - Increase Text Size (Zoom In)

Ctrl+ "-" or Ctrl+ Scroll Down - Decrease text Size (Zoom Out)

Ctrl+ 0 (Zero) - Normal Text Size (Default Zoom Mode)

Alt+ Scroll Down - One step page go down

Alt+ Scroll Up - One step page go Up

Ctrl+Shift+I - DOM Inspector

Ctrl + L or ALT + D - Select Location Bar

Ctrl + Enter - To complete URL with .com

Ctrl + Shift + Enter - To complete URL with .org

Shift + Enter - To complete URL with .net

Ctrl + Up Arrow - Choose previous Search engines to search information

Ctrl + Down Arrow - Choose Next Search engines to search information

Alt + Up Arrow or Alt + Down Arrow - Open List of available Search Engine