Control structures in Java are essential programming constructs that dictate the flow of execution within a program. They enable developers to make decisions, repeat actions, and manage the sequence of operations based on specific conditions. The primary types of control structures include conditional statements, such as if-else statements, which allow for decision-making, and loops, such as for and while loops, which facilitate repetitive tasks. Understanding these structures is crucial for writing efficient and effective Java programs, as they enhance code flexibility and maintainability while allowing for dynamic responses to user input and program states.