Food fit for consumption according to Jewish dietary laws, which cover ingredient restrictions, food preparation, and kitchen equipment.
The Jewish dietary laws (kashrut) cover a wide variety of issues, including ingredients that cannot be eaten (e.g. pork, shellfish), ingredient source (e.g. gelatin), restriction on mixing meat and dairy foods, and keeping kitchen equipment kosher. Ingredients and prepared foods found in supermarkets may be certified as kosher, but certification is not required for an ingredient or dish to be kosher.
A good general overview of what kosher means can be found in What are the requirements for a dish to be kosher? Those interested in further information about the laws of keeping kosher are encouraged to visit Jewish Life and Learning.