In recent years we have seen the explosion of blockchain technology, cryptocurrencies, and all their possible implications. This thesis begins by introducing the technology, explaining the fundamentals of bitcoin, and then seeing how it is being surpassed thanks to ethereum and the creation of the concept of smart contracts and decentralized applications. The blockchain, so-called 2.0, which focuses on the execution of distributed code that is accessible to all lays the foundation for what web3 will be, in the coming years. We will see what are the problems with public blockchain that we see today, so scalability and data security, which makes it difficult for companies to be able to invest in these technologies.