"The Time and Frequency Division, part of NIST's Physics Laboratory, maintains the standard for frequency and time interval for the United States, provides official time to the United States, and carries out a broad program of research and service activities in time and frequency metrology." At this website, visitors can find online exhibits about ethnic and historical calendars, the history of timekeeping, the discovery of the quartz watch, and more. Researchers can learn about the division's studies dealing with ion storage and optical frequencies. Students and educators will find a tutorial about oscillator signals and measurement methods. Through this large website, visitors will understand the intricacies that go into measuring the exact time.