The Advanced Light Source (ALS) is a third-generation synchrotron light source at Lawrence Berkeley National Laboratory. Built in 1993, the ALS serves over 40 beamlines and is one of the world’s brightest ultraviolet and soft X-ray light sources. The 196.8-meter circumference storage ring has an electron beam energy of 1.9 GeV. It supports experiments across various fields, including materials science, biology, chemistry, physics, and the environmental sciences. The ALS is upgrading to become a fourth-generation light source, adding a new accumulator ring and replacing the existing storage ring—the U.S. Department of Energy, Office of Science, Basic Energy Sciences program funds the ALS operation and its upgrade project.