French and English are fundamentally different languages in term of grammar, structure and syntax. Despite this incompatibility, all English speakers understand some French.
The average native speaker will automatically recognise around 1500 French words — without needing to consult a dictionary. This figure expands greatly when a looser connection is included. In fact nearly 30% of all English words come directly or indirectly from French.
The main influx of French words can be traced back to the Norman invasion of England in 1066. Unlike the Romans, the Normans introduced a legal and administrative system written in their own language. The Norman dialect was not generally spoken outside court.