The ID-card is Estonia's compulsory national identity document carrying a chip-based digital identity for online authentication and legally binding digital signatures. It is the backbone of Estonia's e-government, enabling almost all public and many private services online.

Mobile-ID uses a special SIM card to provide card-free authentication and digital signing from a phone, while Smart-ID is an app that works without a SIM. Together they let Estonians authenticate and sign at high assurance without a card reader.

e-Residency is a transnational government-issued digital identity for non-residents, giving a smart card to authenticate and digitally sign documents and run an EU-based company online. It does not grant citizenship, residency, or travel rights.