Fork

When a blockchain has multiple branches, also called “tips of the chain”, and is not sure yet which one is the correct one: $D_0$ and $D_1$ below.

graph TD
	direction LR
    A --> B --> C --> D0?
    C --> D1?

Supposedly, both adhere to the correct STF, but the Consensus Algorithm is yet to decide which one should be decided.

The eventual correct fork is called the canonical chain/fork.