Since their inception, field-programmable gate arrays (FPGAs) have grown in capacity and complexity so that now FPGAs include millions of gates of logic, megabytes of memory, high-speed transceivers, analog interfaces, and whole multicore processors. Applications running in the FPGA include communications infrastructure, digital cinema, sensitive database access, critical industrial control, and high-performance signal processing. As the value of the applications and the data they handle have grown, so has the need to protect those applications and data. Motivated by specific threats, this paper describes FPGA security primitives from multiple FPGA vendors and gives examples of those primitives in use in applications.