Here more insurance info than you'll ever want...
For most people in the US (those who work for a company), their health insurance is part of their employment. the company shops around (in theory) and strikes a deal with an insurance firm. the company pays the bulk of the weekly/b-weekly/monthly contribution to the plan, and the employee contributes a smaller portion. it used to be employees would only contribute $20-30 per month, but companies have tried to cut their costs by shifting more of the burden on employees. I've been self employed for 20+years, so not sure what the empire contribution amounts to at this point but wouldn't surprise me if it's in the $100/month range.
all health insurance policies have deductibles and co-pays. you pay a set amount for every doctor visit -- maybe $30-50 for your GP, $75 for a specialist. and then for all tests, hospital visits, procedures, you chip away at the deductible amount. if you have lots of visit and procedures, you eventually reach the deductible amount and the insurance company pays all or most (80%) of all addition costs.
One issue is insurance is regulated by the states, which all have their own regulations and requirements. You buy a policy from an insurance company registered in your state, and the coverage is good for doctors and hospitals within their network, in that state. if I go to a doctors in my network in NY, my insurance covers the visit. if I find a great doctor in Connecticut, that's outside my insurance company's state network, and I'd have to pay 100% of the out-of-network costs. the exception is emergency rooms visits, which get covered regardless of where you are. if I had to go to the emergency room while on a trip to California, my NY insurance would cover the visit even though it's out of state.