Sake is widely known as Japan’s national drink. It is believed that Japan has been making sake in one form or another for over two thousand years.
Technically, sake just means “alcohol,” so any kind of beer, wine or liquor would be considered sake. What most people mean as, “Japanese Rice Wine” is actually called Nihonshu.
And although it’s referred to as “rice wine,” it’d probably be more accurate to say, “rice beer” because wine is made from fermenting fruit, while beer is made from fermenting grains.
When you warm sake, you need to warm in indirectly, through a separate container, like when melting chocolate. Different temperatures bring out different characteristics, so you can warm it to different degrees for a slightly different taste. Just make sure that you don’t warm it too quickly, and don’t allow it to get too hot.