Understanding Molecular Typography, an artist's book by Woody Leslie, introduces readers to the lost science of molecular typography, the study of the chemical and physical underpinnings of letters. According to molecular typography, all characters are formed from seven basic atomic building blocks: typtoms. These typtoms come together in various combinations to form letters, numbers and punctuation. Typtoms are not just theoretical tools for exploring the anatomy of type, but actual particles. Leslie brings readers a reprint of the seminal 1992 textbook, Understanding Molecular Typography. Part primer, part field guide, the book makes the science of molecular typography accessible to readers. It lays out the basic principles of the field, followed by detailed diagrams of the molecular formation of type. A conclusion sums up the field to date, and a comprehensive bibliography provides valuable reference for the reader looking to learn more.