Clicking item or stack will move it between inventory and stack

When a container is open, Shift + clicking on an item will move up to a stack between the container and the inventory

Toggle showing hitbox around entities

Cycle the player's game mode between Creative and Spectator

Toggle heads up display (HUD)

When crafting, Shift + clicking the crafted item automatically crafts the maximum number of that item for the materials being used (up to one stack), and moves all crafted items to the inventory

Toggle detailed item descriptions

Show the chunk boundaries immediately surrounding the player

Sprint

Pause single player game

When a furnace is open, Shift + clicking an item or stack in the furnace moves it to the inventory

Toggle showing extra debug information

Drop whole stack of items. On Mac, use shortcut below, because this shortcut will quit game

Scroll through quick-bar and the chat when opened

Display more detailed view of the graph on the right

In the survival inventory tab of the creative inventory, Shift + clicking the X clears the whole inventory. In any other tab, Shift + clicking an item puts a stack into the hotbar

Toggle the auto-pause when the window is out of focus

Exit the chat / command window

Open the menu and give back cursor control

Reload all textures, sounds and web-loaded client resources. This is useful for resource pack makers

Reload all chunks

Display Profiler graph

Pick block

Use with F1 to take screenshots without HUD

Clear chat history, including previous commands

Hotbar slot

Use item / place block

Hold these keys at least for 6 seconds to trigger a manual debug crash on purpose, after the keys are released

Toggle perspective

In the Multiplayer server selection menu, Shift + up and Shift + down moves a server name to a specific position. You can also hold shift while a server name is selected left click another server name and they will swap

Drop item

Display less detailed graph

Open Inventory. Close any open GUI

(in chat window) Cycle through possible commands or arguments and also complete player names

Display Help menu that lists all F3 shortcuts

Swap items in hands

Sneak

Take screenshot

Strafe left

Advancements

Toggle full screen

Open chat

(Mac) Drop whole stack of items

Load toolbar activator

See the list of players

Walk backward

Attack / destroy

Save toolbar activator

Strafe right

Open command (open the chat window with "/" character already typed")

Walk forward

Jump

(double tap) Toggle Fly Mode in Creative mode