More than anything else, sake is a result of a brewing process that uses rice and lots of water. Please visit the Ingredients page for a detailed review of these five crucial ingredients. A general description of sake brewing looks something like this.
Rice is washed and steam-cooked.
The whole mix is then allowed to ferment, with more rice, koji, and water added in three batches over four days. This fermentation, which occurs in a large tank, is called shikomi. The quality of the rice, the degree to which the koji mold has propagated, temperature variations, and other factors are different for each shikomi. This mash is allowed to sit from 18 to 32 days, after which it is pressed, filtered and blended. This would be enough to get you through most conversations.