Block censorship occurs when a miner or validator refuses to include specific transactions in a new block. This can happen for various reasons, such as political motives, legal pressure, or the desire to control network usage. When block censorship occurs, it can undermine the principles of decentralization and fairness that many cryptocurrencies strive for.

Users whose transactions are excluded may face delays or be unable to conduct their business. Censorship can take many forms, including the refusal to confirm transactions associated with specific addresses or the blocking of transactions related to controversial activities.

This raises concerns about freedom of expression and the potential for abuse by those in control of the network’s infrastructure. However, decentralized networks are designed to make censorship challenging. If multiple miners or validators act independently, it becomes harder for any single entity to block transactions consistently.

Thus, while block censorship can occur, the open and transparent nature of these systems often provides mechanisms to counteract and reduce the impact of such actions.