ASML is the leader in photolithography systems used in the manufacturing of semiconductors. Photolithography is the process in which a light source is used to expose circuit patterns from a photo mask onto a semiconductor wafer. The latest technological advances in this segment allow chipmakers to continually increase the number of transistors on the same area of silicon, with lithography historically representing a high portion of the cost of making cutting-edge chips. ASML outsources the manufacturing of most of its parts, acting like an assembler. ASML's main clients are TSMC, Samsung, and Intel.