How do sequence, conditional, and iterative structures control a computer program?

In procedural computer programming languages, control structures dictate the flow of execution. These three fundamental structures allow programmers to organize instructions effectively:

• Sequence: This is the default structure where instructions are executed one after another in a linear order. It is typically used for performing a series of operations, such as arithmetic calculations.
• Conditional: Using structures like IF-THEN or IF-THEN-ELSE, this allows a program to evaluate specific conditions and follow alternative paths of execution based on those results. This is essential for handling logic and checking assumptions within a program.
• Iterative: Also known as looping, this structure enables a computer to repeat a sequence of steps as often as necessary. Iteration provides significant computational power, as it allows simple steps to solve complex problems through repetition.

These structures can be combined, nested, or used within subprograms to break down complex tasks into manageable parts. At the machine level, these are implemented via branch instructions, though higher-level languages prioritize structured flow over simple "jump" commands to maintain readability.1