Control structures in JavaScript, such as loops and conditionals, are fundamental for managing the flow of a program. Conditionals, like if, else if, and else, allow the program to make decisions and execute different code blocks based on specific conditions. For instance, an if statement evaluates a condition, and if it’s true, the associated block of code runs; otherwise, it moves to the else or else if blocks, if provided.

Loops, including for, while, and do...while, are used to repeat code multiple times. The for loop is typically used when the number of iterations is known beforehand, such as iterating over an array. The while loop continues to execute as long as its condition remains true, making it suitable for scenarios where the number of iterations is not predetermined. The do...while loop is similar but guarantees that the loop body executes at least once, as the condition is evaluated after the loop’s code block.