Vanilla minecraft has some basic keybinds, but it's not enough (for some people at least)!
NotEnoughKeybinds mod adds lots of somewhat useful keybindings and a decent keybinding preset system.

Do you prefer a PvP friendly version? Download Just Enough Keybinds instead!

Inventory Management

• Throw Ender Pearl & Wind Charge

  If you have an ender pearl or a wind charge on your inventory, you can throw it using this binding.

  

• Swap Totem of Undying and Shield

  Quickly swap totem and shield when you are holding them. You can even use this as "manual" auto totem.

  

• Equip Elytra (auto elytra)

  Equip an elytra with one key and start flying. When you press that key again, chestplate is equipped back. If this
  keybinding is bound to the same key as jumping is, the autodetect feature is turned on, meaning, you can jump in the
  air as if you had an elytra, and the elytra is equipped. Upon landing, your chestplate is swapped back.

  

Chat/Command Hotkeys

Do you have a command or a message that you send a lot? Bind a key to it!

Keybind Presets

You can save and load as many presets as you'd like. You can even use hotkeys, to load them mid-game.

Building keys

The most useful binding from this category is called Air Place Yes, you can use this to place blocks in the air.

Other Features & Bindings

• Toggle Second Skin Layer(s)

• Rebind F3 debug key

  Debug keys like F3 + B are no longer hard coded (this feature is no longer needed for mc 1.21.11+).

• Music & Sound keys

  Toggle sounds by clicking a button.

• F3 Debug keys shortcuts

  If you use some debug key a lot, you can bind it to whenever key you'd like.

• Reset all keys confirm screen

  No more accidental keybind resetting.

• Toggle in-game HUD

  Adds the ability to rebind F1 (also not needed for 1.21.11+)

• Diconnect Keybind

This mod may be viewed as an unfair advantage by some servers. Use it at your own risk.