Biotechnology is the use of living things to make or change products, such as the food we eat. Until the 1950s, traditional biotechnology was a pretty imprecise and time-consuming affair. If you wanted to produce a particular variety of wheat that ripened early, you'd spend a long time cross-breeding different types and hope that you got the traits, and only the traits, that you wanted. DNA is deoxyribonucleic acid, a chemical molecule which contains in its long strands segments called genes, which are found in almost every cell of all living things. Each gene acts as a set of instructions coded with the genetic information which gives all living things their particular characteristics.
Many characteristics are the result of a complex collection of different genes.
It's all in its structure. This discovery won James Watson and Francis Crick a Nobel Prize for Medicine in 1962. Strands of DNA are twisted in pairs to form a shape called a double-helix. These bases are repeated along every length of DNA in linear sequences of A's, G's, T's and C's, and its these sequences that are the morse-like genetic code for individual genes. It's rather like a library.