The European Health Insurance Card (EHIC) allows access to medical care in the 27 countries of the European Union (plus Norway, Iceland, Liechtenstein and Switzerland). However, it does not replace travel insurance, as it does not cover services such as repatriation, the transfer of family members, or other common coverages. It also does not guarantee that healthcare will be completely free; in some countries, it will be necessary to pay the costs at the time and request reimbursement later.
Therefore, although it is not mandatory, it is advisable to take out insurance when traveling in Europe. For trips outside of Europe, international travel insurance is much more important, as some countries do not have free public healthcare and medical costs can be high.