When talking about Decentralized systems it refers to an interconnected information system. In this kind of network, no single entity is the main authority. Within the field of Computing and Information technology, systems that are decentralized are usually networked computers.
Within a Decentralized system, nodes and actors work together in a distributed manner so as to achieve a more unified goal. One such example is the internet. But then, recently the internet had become under the control of a centralized system.
A Decentralized system must be distinguished from a Distributed system. The main difference being, in a Decentralized system, there is a presence of multiple authoritative nodes serving a subset of total end users. In a Distributed system, however, no end-users could be found as every node on the network communicates with each other so to behave like a single unit.