Caps

When each human reaches the age of maturity, usually fourteen, they are taken by the Tripods to be capped. These caps control the human's thoughts and emotions, making them easier for the Masters to control, keeping rebellions non-existent.

Books

The Masters have collected a library of books from the humans who existed when they conquered the Earth. Will's Master allows him to take some of these books to read. Will's Master has also read these books and finds human behavior curious, leading him to ask Will many questions about human behavior.

Gas Bubbles

The Masters use gas bubbles of some sort to become intoxicated. When Will's Master has too many of these gas bubbles, he beats Will. Later, when Will kills his Master, he and Fritz make it appear that the Master had too many gas bubbles and fell into his water pool.

Air Masks

While living...