Ingame helpful controls

F1 = Hide GUI
F2 = Take Screenshot
F3 = Debug Info (includes coordinates)
F3 + Shift = Toggles Profiler
F3 + A = Reload Chunks
F3 + B = Shows Hitboxes
F3 + C = Manual Crash
F3 + D = Clear Chat History
F3 + F = Increase Render Distance by 1
F3 + F + Shift = Decrease Render Distance by 1
F3 + G = Toggle Chunk Borders
F3 + H = Advanced Item Tooltips (adds detail for most tools, ie the number of hits remaining on a pickaxe)
F3 + N = Toggle Between Spectator & Creative Modes
F3 + P = Toggles Game Pause (allows for Alt + Tab without having the menu appear)
F3 + Q = Show All F3 Key Combinations
F3 + S = Reload Sounds and Textures
F3 + T = Reload all sounds, textures, models and other content that was added/changed by a resource pack
F3 + Alt = Shows FPS Graph
F5 = Toggle Camera View
F8 = Toggle Smooth Camera
F11 = Toggle Full Screen

1-9 Keys (not numpad) = Quick Move to/from Hotbar
F = Switch Items Between Off Hand and Main Hand
Q = Drop Single Item
Q + Ctrl = Drop Entire Stack of Items
T = Open Chat

Left Shift = Sneak (allows you to get close to the edge of blocks without falling)
Tab = Shows Player List, auto completes commands, usernames etc
Ctrl (or double-tap W) = Sprint

Middle-Click Mouse = Pick Block (will move block you click onto hotbar if it’s in your inventory in survival)
Right-Click Mouse (on stack in inventory) = Grabs half of the stack
Hold Right-Click Mouse (in crafting grid/inventory) = Distributes only one of the item held in each slot you mouse over
Hold Left-Click Mouse (in crafting grid/inventory) = Evenly distributes the item held in each slot you mouse over
Left-Click Mouse + Shift (in crafting table) = Crafts as many of item as possible
Double Left-Click Mouse = Grabs all of one item (up to a full stack)
Double Left-Click Mouse + Shift (while hovering over item) = Moves all of the same item from inventory to chest or vise versa)