This book illustrates advanced technologies for imaging electrons and atoms in action in various forms of matter, from atoms and diatoms to protein molecules and condensed matter. The technologies that are described employ ultrafast pulsed lasers, X-ray free electron lasers, and pulsed electron guns, with pulse durations from femtoseconds, suitable to visualize atoms in action, to attoseconds, needed to visualize ballistic electron motion. Advanced theories, indispensable for understanding such ultrafast imaging and spectroscopy data on electrons and atoms in action, are also described. The book consists of three parts. The first part describes probing methods of attosecond electron dynamics in atoms, molecules, liquids, and solids. The second part describes femtosecond structural dynamics and coupling of structural change and electron motion in molecules and solids The last part is dedicated to ultrafast photophysical processes and chemical reactions of protein molecules responsible for biological functions.