The University of SydneyPage 35Blockchain Forks–When a new block arrives, the node will try to slot it into the existing chain based on the “previous block hash” field.–Nodes maintain three sets of blocks;–Main blockchain–Secondary chains –Branches of the main blockchain–Orphans –Blocks that do not have a known parent–Bitcoin consensus–Chain of blocks has the most cumulative difficulty associated with it at any given time.–Often this is the chain with most blocks in it, unless there are two equal length chains and one has more proof-of-work.