We're almost 9 months into our outbreak, and - by and large - Americans still don't understand these terms, or the importance of doing them properly.
Models of infection spread AND direct observation from countries that are doing this show that a good program of isolation, quarantine and contact tracing can nearly bring Rt below 1 by themselves. Even done imperfectly, they can do the bulk of the work without requiring much change in daily lives.
Unfortunately, some of these steps would require a loss of income for people who absolutely can't afford it. We need an easy-to-use federal program to compensate individuals or employers for the losses that come from bona fide isolation and quarantine periods, while preventing most freeloader abuse. More on that later.
We need public education and an attitude shift toward proper behavior on symptom onset. If you have two or more symptoms that could be COVID-19, you need to isolate until testing can confirm or clear you. (A negative PCR test is a very reliable indicator, a rapid antigen test if you're symptomatic is fairly reliable.)
Isolation means staying at home, and quarantine for your your household members. (We should also fund hotel isolation free of charge for people who want to spare their household members.)
Quarantine means staying at home to avoid spread until you know if you've been infected. Unfortunately, this can take over a week, possibly two week from date of exposure. It shouldn't be necessary to quarantine your unexposed household members until you know your test status.
Contact tracing is the key to stopping the spread - alerting people who have been exposed, and getting them to quarantine and test before they infect others.
State workers specializing in contact tracing are a key resource, but informal contact tracing with friends, family and coworkers can get a very quick start.
Contact tracing in public areas - stores, restaurants, churches - gets a little more complicated. A system of QR codes and coordinated apps can simplify the process. These contacts may not require quarantine, but may want to do a rapid antigen test now and a follow-up in a few days, or just be extra vigilant for any symptom onset.
Apple and Google bluetooth apps can provide similar anonymous warnings, but their effectiveness depends on widespread use.