Abstract: Optical lattice clocks (OLCs) are now the most stable and accurate timekeepers in the world, with fractional accuracies equivalent to neither losing nor gaining a second over the entire age of the universe. This unprecedented level of metrological precision offers sensitivity to new quantum, many-body, and fundamental physics effects, opening the door to exciting and unusual applications. This talk will provide an introduction to how and why time is measured, with an emphasis on OLCs and their applications. I will discuss recent progress on pushing OLCs to even greater levels of precision, as well as prospects for future improvement. I also will present results from a recent experiment in which we harnessed the precision of an OLC to simulate complex condensed matter phenomena. Finally, I will give a brief overview of emerging applications of OLCs, including research taking place here at UW-Madison into using clocks for gravitational wave detection, tests of general relativity, and searches for physics beyond the Standard Model.