Thu'um is a powerful form of magic in the Elder Scrolls universe, specifically known for its use by the Dragonborn. It involves the use of ancient words of power, called Shouts, which can unleash devastating effects on enemies or alter the environment. Each Shout consists of three words, and the more words used, the more powerful the effect. The ability to use Thu'um is derived from the teachings of the Dragons, who originally mastered this form of communication and magic. The Dragonborn can learn and harness these Shouts by discovering Word Walls scattered throughout the land, allowing them to become formidable warriors.