Metroid Prime 3's Logbook grants you a complete journal of recorded objects, creatures and all sorts of interesting intel from the worlds of the game. Press 1 and select the Logbook icon (small book, on the left below the map icon) to view the entries recorded so far.
Most objects of interest in the game can be scanned, so it's always a good idea to fire up the Scan Visor while entering new areas (hold Minus and point to the top of the screen). Scannable objects glow brightly green, red or blue. Information gathered from objects can give you anything from simple observational data right up to strategies for dealing with tougher enemies. Much of the game's story is also told through simply scanning and gathering information from the environments.
Objects reside in one of three categories - Creatures, Lore or Research. As you scan new objects they'll automatically be added to the right category, filling in a blank slot. Unlike the previous Logbooks, when you finish the game and restart from the beginning (saving to the same save slot) you'll retain all your scanned items; all set to hunt for any entries you may have missed.
Scanning certain objects for the first time will also reward you with credits. Scanning each creature in the game will reward you with a red credit, while scanning each lore item rewards you with a blue credit.
See below for a complete listing of all the Logbook items and where to find them in the game. Items noted with a * are critical - on your first encounter scan it immediately as you'll only have either one or very few chances to do so. As you fill up the Logbook, unlockable items in the Extras menu will gradually become available.
Please note: Special thanks to Metroidologist for this note. The Creatures list here is based on the Logbook's presentation in the original PAL and Metroid Prime Trilogy versions of the game; the original NTSC version doesn't have a separate Bosses section and instead categorises the boss characters within the other sub-categories. The Despair-Class Turret (a green variant of the Remorse-Class Turret, found in the Pirate Homeworld) also only appears in the Logbook of the original PAL and Metroid Prime Trilogy versions.