There are many different ways to mash. These come from different regions as brewing traditions developed. They were developed from trial and error efforts of the brewmasters and passed along to new generations and refined.
Today these mashing methods have been perfected with careful measurements and the knowledge of those who came before. Many of the historical methods have altogether disappeared or have faded to the background as the malting process has increased efficiency reducing the need for some of the time consuming processes (and obviously expensive processes for professional brewhouses). Left are a handful of processes that are typically used. Here those processes are outlined.