To be honest, I too didn’t know until I stumbled on it by error. While trying to reply a message I unknowingly typed a character I didn’t take notice of and a pop up showed on the screen of my laptop with all the buttons to press on the keyboard to use Facebook faster. Things like this do happen!
You can press these buttons on your keyboard to use Facebook faster.
j, k — Scroll between News Feed stories
p — Post a new status
l — Like or unlike the selected story
c — Comment on the selected story
s — Share the selected story
o — Open attachment of the selected story
enter — See More of the selected story
/ — Search
q — Search chat contacts
? — Show this help dialog
Alt + 0 — Help
Alt + 1 — Home
Alt + 2 — Timeline
Alt + 3 — Friends
Alt + 4 — Inbox
Alt + 5 — Notifications
Alt + 6 — Settings
Alt + 7 — Activity Log
Alt + 8 — About
Alt + 9 — Terms
Alt + m — New Message
These keyboard shortcut may not work as stated above in other browsers but they are sure to work well on Chrome. You can try it for yourself.