Random samples of, usually, around 1000 people out of those people who can be reached, after all sorts of weighting and selection. 1000 adults out of say 200,000,000 is a tiny probability of selection for any given national poll.
I’ve been polled maybe 5-6 times in 30 years, and my wife more, probably because she was not working while raising the kids. Maybe because we had a landline phone the whole time.
The trouble with polls is the massaging of the responses by the pollsters to get what they consider to be representative samples after the data is collected. That’s how you get a Democrat-skewed sample.
Polls are BS...maybe always have been....Just a tenacle of the MSM