To complete the analogy, you need to have one concurrent session per "virtual user." This is the "concurrency" of the test. In my bad test, I had one concurrent

To complete the analogy, you need to have one concurrent session per "virtual user." This is the "concurrency" of the test. In my bad test, I had one concurrent user driving all the throughput--me. If I had targeted 200 concurrent users, I would have seen a failure in my test and found what the real throughput would be. Each concurrent user uses many resources that could be limited. In the restaurant, it is tables, plates, silverware. In a web app, it is sessions, connections, memory, database connections, and many other resources that can be associated with each session, and each may be a potential bottleneck that limits your actual throughput. If we target throughput and ignore concurrency, we set ourselves up for failure. In practicality, the better load testing tools let you create "concurrent users." In JMeter, this is the "threads." In other tools, it will be called "virtual users", "vus" or "sessions." In locust, the setting is -u NUM_USERS. The caution is not to fool yourself with high RPS if these settings aren't right for your test, and to normally target both.