What does the term 'co-insurance' refer to in an insurance context?

The term 'co-insurance' in an insurance context specifically refers to the portion of expenses that the insured is responsible for after meeting any deductible requirements, in a typical health insurance plan. This means that once the insured has paid their deductible, they will share the costs of covered services with their insurance provider, usually expressed as a percentage.

For instance, if a health insurance policy has an 80/20 co-insurance clause, the insurance company pays 80% of the costs for covered services, while the insured is responsible for the remaining 20%. This arrangement emphasizes the shared responsibility between the insurer and the insured when it comes to healthcare expenses.

In contrast to this, other options in the question refer to either the payment of premiums (which relates to the cost of insurance coverage), the concept of a policy that covers 100% of expenses (which would not typically involve co-insurance), or government assistance that provides financial support for medical costs. These do not accurately represent the definition of co-insurance as it involves the active participation of the insured in sharing the cost of their healthcare.