A blockchain divergence (fork) happens when multiple blocks are mined at the same time or when a malicious node has confused the network which causes differing blocks to appear. From this point on, the blockchain diverges into multiple chains.Miners will choose to create blocks on the longest available branch (the one with the most blocks). Once the correct branch has been settled on, the shorter branches are thrown out and their blocks will not pay mining rewards to those who mined them. Therefore, miners are incentivized to ensure their blocks go on the longest branch together. This incentive means that the miners will focus on a single chain, which means that diverging chains will resolve into a single chain.