In brief
An autolyse is a rest after mixing flour and water, before the main kneading stage.
Useful to know
An autolyse is a rest after mixing flour and water, before the main kneading stage. King Arthur describes it as a way to hydrate the flour and begin developing the dough. [1]
It is not another name for fermentation. In the classic approach, salt and the leavening culture are added later, although individual recipes vary. Follow the complete formula, including any water reserved for later additions. An arbitrarily long rest does not guarantee better bread and is not equally suitable for every flour.
Sources
For further detail and to check the information: