Sandwiches are snack foods comprising two or more slices of bread, usually buttered, enclosing sweet or savoury fillings such as meat, fish, cheese, eggs, or jams. Variations include open sandwiches and toasted sandwiches, and commercial pre-packed sandwiches form an important part of the fast-food sector in many countries. Because fillings are often ready-to-eat and handled extensively, chilled storage and strict hygiene are essential to keep them safe. Date marking and chilled display are the main safety controls in sandwich retail.