Just like other insurance products, health insurance has its own jargon. You should be familiar with these terms before signing up for a policy. Majority of insurance companies ask you to undergo a physical before they underwrite you for a policy. That's because the result of your physical will determine how much your rate or premium will be for your health insurance coverage.
There is a chance that some insurance providers will not do their due diligence in the beginning (comparing your physical to your completed application or questionnaire) and will instead play the odds that you won't get sick, injured or suffer some other health catastrophe.
But if and when you do get sick, they will analyze your records hoping to find reason not to compensate your health insurance claims. If and when they find that loophole, they may try to not entertain your claim or cancel your insurance completely. Take note, however, that it's not all health insurance companies which do this but an extremely small percentage who practice this m.o. so you won't receive what is due you.
This is why you must be very careful of who you choose and do your research on them and their ratings. Thankfully you can easily find this information over the internet.
Always make sure your application you fill out contains full disclosure and a complete and accurate assessment by you regarding your health otherwise you may find a future health related claim denied.
In some cases the health insurance agent for the company or provider you are considering will fill out the health insurance application for you. If this happens, you must make sure and double check it for accuracy. Remember agents get paid based on the business they provide to the insurance company so always make sure no shortcuts were taken to get you initially covered by the health provider. If your future claims get denied due to an error on your initial application it doesn't really phase the insurance agent hat helped you in the beginning.