Blockchain technology represents a new and exponentially growing technology. It has the potential of being one of the more promising ones in the future. As part of the Master’s thesis, the technology was explained and one example was created. For a better understanding of blockchain technology, the concept of cryptography and the basic algorithm are explained at the very beginning of the thesis. Firstly, the difference between decentralized and centralized systems is clarified, which is essentially how blockchain differs from other technologies. Also, the historical development of blockchain technology is included, with pivotal events that led to the growth and interest of the wider population in it. Furthermore, the development of the Internet over the years is explained with the key features of web3 technology, which represents the night era of the Internet revolution based precisely on blockchain technology. In the next chapter, the fundamentals of blockchain work are explained, including the principles of reaching consensus. The concept of smart contracts, which are an integral part of the functioning of blockchain technology, is also clarified. Additionally, there are examples for which the mentioned technology can be used including the benefits it would provide. As part of the thesis, an application based on blockchain technology was made using a smart contract. A decentralized application was created for the exchange of messages between application users. Decentralized applications (dApp) represent a new generation of the Internet that provides the user with the freedom and privacy to use the Internet, without the monitoring and control of large technological giants. React was used to create the above mentioned application and Solidity was used to create the user interface and smart contract.