The trapped-ion architecture was the first platform to demonstrate quantum gate operations in 1995 and continues to be a leading candidate for building a fault-tolerant quantum computer. This chapter provides a brief background on common performance metrics and nomenclature, summarizes the state of the art, and places them in context within the larger pursuit of error-corrected quantum computers. Current research thrusts in academia and industry are referenced, and an example roadmap is examined to show where the platform is right now and where it might be headed on the road to realizing a scaled-up device.