Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The structured program theorem is a result in programming language theory. It states that every computable function can be implemented in a programming language that combines subprograms in only three specific ways. These three control structures are 1. Executing one subprogram, and then another subprogram (sequence) 2. Executing one of two subprograms according to the value of a boolean variable (selection) 3. Executing a subprogram until a boolean variable is true (repetition)