I got a couple PCR tests last year when I wanted to be sure I was healthy — after coming home from college to visit my family, for instance. I trusted the gold-standard test wouldn't steer me wrong, especially if I quarantined before taking it.
Since then, rapid antigen tests have become more widespread. Antigen tests quickly scan for fragments of the virus' genetic material, which is a good way to know if you're infectious or not. But they don't detect the virus with as much sensitivity as PCR tests, so there's a greater chance of getting a false negative.
The convenience of getting a result in 15 minutes appealed to me, but I knew I would have to take it with a grain of salt. Experts say rapid tests are most helpful if used for frequent screening, like testing every three days.