Blockchain is a digital technology for storing and transmitting data that operates without a central authority. It relies on a distributed database where information is grouped into interconnected blocks, forming a secure and transparent chain. This technology guarantees data integrity by preventing any unauthorized modification. It comes in two forms: public blockchains, accessible to everyone, and private blockchains, with restricted access. Emerging in the late 2000s with the creation of Bitcoin, blockchain offers a wide range of applications across various sectors.