This is a process for converting grain starches to fermentable sugars by enzymes and some other compounds. The most important enzymes are alpha-amylase and beta-amylase.

Alpha-amylase: for more complex, less fermentable sugars-full body, sweet, malty beer types. Temperature range: 67 – 72 °C / 152,6 – 161,6 °F, it has best effect at lower end of temperature range.

Beta-amylase: for simple, more fermentable sugars-higher alcohol and more dry beer types. Temperature range: 55 – 65 °C / 131 – 149 °F, it has best effect at higher end of temperature range.

Mashing consists of: 
1. Mashing-in
2. Protein pause
3. Sugar pause
4. Mash-out

So according to above, the best temperature range for mashing is 65 – 68 °C / 149 – 154,4 °F. If you want to make sweeter, more light beer you should mash at higher temperatures (close to 68 °C / 154,4 °F) – enzymes converts less fermentable sugars. If you want to make stronger beer use lower temperatures (close to 65 °C / 149 °F) – enzymes converts more fermentable sugars.

We use either single infusion mash or multiple step mash. There also is decoction mash, but I do not use it.

Single infusion mash
Our goal is to maintain the temperature for at least 60 minutes.

Multiple step mash
We start mash at lower temperatures, raise temperature, stop heating and make a rest, and so on and on. It depends on which sugars we want to convert.

Equipment for mashing: 

Video of Single infusion mash: