Crystal

Crystal malt, also known as caramel malt, is a specialty malt that adds color and flavor to beer, achieved by heating wet, germinated barley in a closed system, resulting in a crystallized endosperm and a range of caramel-like flavors. 
Here's a more detailed explanation:
What is Crystal Malt?
Specialty Malt:
Crystal malt is a type of specialty malt, distinct from base malts like pale malt. 
Unique Production:
Unlike pale malts, which are kilned (dried), crystal malts are heated in a closed system, allowing moisture to remain and caramelize the sugars within the grain. 
Color and Flavor:
This process results in a range of colors and flavors, from light caramel to dark, roasted toffee notes. 
No Enzyme Contribution:
Crystal malts do not contribute enzymes to the mash, so they are used primarily for their color and flavor contributions, not for their ability to convert starches to sugars.