A deductible is the amount of money that you or your family has to pay out of pocket before your insurance starts making payments on your behalf. This is a fairly universal concept in all types of insurance.
A health insurance deductible will range between no deductible and $6,900 for an individual and $13,800 for a family. After you have paid your providers that amount in total for a calendar year, then your deductible obligation is complete, and you will only be required to pay your copay percentages up until the point that you have met your out-of-pocket maximum.
Again, remember, the health insurance deductible and out-of-pocket maximum are amounts that reset annually.
Choosing a lower deductible health insurance plan will usually result in a higher monthly cost, but will generally result in lower out of pocket expenses beyond your monthly premiums. A high deductible healthcare plan (HDHP) that is eligible for a healthcare savings account (HSA) may also provide you a way to cover your healthcare costs in a tax-advantaged way now or provide you with another type of retirement account later.