Ship-biscuit, also known as HARDTACK, is a type of simple biscuit or cracker made from flour, water, and sometimes salt. It has been used for centuries as a cheap, long-lasting, and nutritious food staple, especially in the military. HARDTACK is usually made into large, thin, rectangular shapes that can be stored for long periods of time without spoiling. It is often eaten as a snack or with other foods such as cheese or jam.