Decentralization describes a system where control and decision-making are spread across many participants instead of concentrated in one central authority. In crypto, it means a network is run by many independent computers around the world rather than a single company or government.
The appeal is resilience and openness. With no central point of control, there is no single party that can shut the network down, censor transactions easily, or unilaterally change the rules. It also means no single point of failure, since the network keeps running even if some participants go offline.
Decentralization is not all-or-nothing; networks sit on a spectrum. Some are highly decentralized with thousands of independent participants, while others are more concentrated. Understanding where a project falls on that spectrum helps you judge how much it truly relies on distributed control versus a smaller group of decision-makers.