I don't really know more. What I known is that there is a process know as fermentation
Bread has to proof, or rise, before baking.  The process is known as fermentation.  Beer froth helped this process.
My friend has been sending me pictures of all the baked goods she has made recently. She must be so talented to be a baker! Does she bake bread? I know that the Gauls discovered that beer froth made well-leavened bread. Yes, but I don't think she has ever used beer froth before! Can you tell me more?
It refers to a specific rest period within the more generalized process known as ''fermentation''.