When Estonian political and technical leadership began laying the foundation for e-Estonia, it decided on certain principles:
Decentralization. There's no central database, and every stakeholder, be it a government department, a ministry or a business, gets to choose its own system in its own time.
Interconnectivity. All the elements in the system have to be able to work together smoothly.
Open platform. Any institution can use the public key infrastructure.
Open-ended process. As a continuous project to keep growing and improving organically.
The two key ingredients in the infrastructure are the X-Road and e-Identity or e-ID. The X-Road is a critical tool that connects all the decentralized components of the system together. It's the environment that allows the nation's various databases and registers, both in the public and private sector, to link up and operate in harmony no matter what platform they use. eID is the nationally standardized system for verifying a person's identity in an online environment. It opens the door to all secure e-services while maintaining the highest level of security and trust.
Other systems have since been linked, thanks to these. But the Estonian government didn't create programming resources – it acted as a smart purchaser. The licenses belong to the taxpayer, but the solutions were created by private companies. That way costs were reduced, while flexibility was maintained.