The Estonian identity card (Estonian: ID-kaart) is a mandatory identity document for citizens of Estonia. In addition to regular identification of a person, an ID-card can also be used for establishing one's identity in electronic environment and for giving one's digital signature. Within Europe (except Belarus, Russia, Ukraine and United Kingdom) as well as French overseas territories, Georgia and Tunisia (on organized tours only) the Estonian ID-card can be used by the citizens of Estonia as a travel document.

The mandatory identity document of a citizen of the European Union is also an identity card, also known as an ID card. The Estonian ID-card can be used to cross the Estonian border.

With the Estonian ID-card the citizen used to receive a personal @eesti.ee e-mail address, which was used by the state to send important information. This service was discontinued in 2023.

The Police and Border Guard Board (PPA) on 25 September 2018 introduced the newest version of Estonia's ID-card, featuring additional security elements and a contactless interface. The new cards also utilizes Estonia's own font and elements of its brand. One new detail is the inclusion of a QR code, which makes it easier to check the validity of the ID-card. The new design also features a color photo of its bearer, which doubles as a security element and is made up of lines; looking at the card at an angle, another photo appears. The new chip has a higher capacity, allowing the addition of new applications to it.

The Estonian ID-cards are used in health care, electronic banking, signing contracts, public transit, encrypting email and voting. Estonia offers over 600 e-services to citizens and 2,400 to businesses. The card's chip stores digitized data about the authorized user, most importantly: the user's full name, gender, national identification number, and cryptographic keys and public key certificates.

There are several types of identity documents issued by the Estonian state that are usually referred to as the Estonian ID-card. These are the identity card, the digital identity card, the residence permit card, the e-resident's digital identity card and the diplomatic identity card.

While these identity documents are issued to different categories of persons and have a different appearance, all these documents provide the same electronic functionality via a smart card chip.

From its introduction in 2002 until now, the core electronic functionality provided by the Estonian ID-card has stayed the same. The ID-card contains two asymmetric (RSA or ECC) key pairs with the corresponding X.509 public-key certificates, and symmetric keys to perform card management operations.