Emerging technologies have revolutionized a new generation of atomic clocks. In this lecture, the most accurate clock in the world, designed and developed in the laboratory at JILA in Boulder, Colorado, will be described. The clock has an eighteen-digit accuracy and does not vary more than a fraction of a second in 15 billion years, that is over the entire age of the Universe. The design of this clock is based on quantum state engineering of ultracold atoms using laser beams and other means. Such accurate atomic clocks and the related technology of ultrastable lasers have a variety of applications in research into fields like dark matter, changes in Earth’s gravity, precision metrology, and fundamental physics. In the coming years, we will see a range of wider applications in computing and other aspects of every day life.