Biosimilars are biological medicinal products that are highly similar to approved reference biologics but produced by a different company after patent expiry; they undergo rigorous evaluation of structure, purity, activity, pharmacokinetics, and no clinically meaningful differences to ensure the same efficacy and safety; savings may reach 30% with projected savings up to $100 bn; examples include Adalimumab and Trastuzumab biosimilars; barriers include patent strategies and exchange hesitancy, though some are designated interchangeable allowing pharmacy-level substitution.