Slashing is a bakery term which refers to slashing the top of the dough with a very sharp knife or razor blade. This is crucial – a blunt knife simply won’t do the job properly.
As well as giving the bread an attractive appearance, historically – in the days of communal ovens – it was also the baker’s signature which enabled easy identification of which loaf belonged to whom.
Slashing the dough also has a practical function. It controls where the dough bursts during the rapid expansion which happens in the first stage of baking. This leads to a better texture of the loaf as well as making it look better.