The White Book, formally called The Book of the Brothers, is the tome that records the deeds of every member who has ever served in the three hundred year history of the Kingsguard.
It is two feet tall, a foot and a half wide, and a thousand pages thick. The book is kept in the Red Keep in the White Sword Tower, where the knights of the Kingsguard have their sleeping cells. The book is in the common room on the first floor of the tower in the room where the seven meet. It is the responsibility of the current Lord Commander of the Kingsguard to update the entries in the book.
Each member has one page to record his deeds and exploits in. Each knight who has been made a member of the Kingsguard since the reign of King Aegon I Targaryen has a page within the book detailing his deeds. On the top left-hand corner of the page his personal arms are drawn while at the bottom right-hand corner are the arms of the Kingsguard. The drawings are done by septons from the Great Sept of Baelor and are sent three times a year.
A Storm of Swords
The one-handed Jaime later awkwardly updates his own entry.
A Feast for Crows
I'll hack the bloody book to pieces before I'll fill it with lies. Yet if he would not lie, what could he write but truth?—thoughts of Jaime Lannister
Barristan Selmy was not a bookish man, but he had often glanced through the pages of the White Book, where the deeds of his predecessors had been recorded. Some had been heroes, some weaklings, knaves, or cravens. Most were only men—quicker and stronger than most, more skilled with sword and shield, but still prey to pride, ambition, lust, love, anger, jealousy, greed for gold, hunger for power, and all the other failings that afflicted lesser mortals. The best of them overcame their flaws, did their duty, and died with their swords in their hands. The worst ... The worst were those who played the game of thrones.—thoughts of Barristan Selmy