An epoch is a predetermined period of time in the world of cryptocurrencies during which blocks are generated and added to the blockchain. Depending on the specific cryptocurrency, an epoch’s length can change. For instance, the current epoch lengths for Ethereum and Bitcoin are 12 seconds and 10 minutes, respectively.
By employing an epoch system, it is possible to guarantee that every node on the network is aware of the exact time that each block was produced. This aids in preventing blockchain forks (or splits), which can result in mistakes and inconsistent data.