Repetition statements (loops) allow code to execute multiple times. There are three types of loops in Java: while, do, and for. The while loop continuously executes a block of code as long as a condition is true. It checks the condition, executes the code, then re-evaluates the condition. An example prints a message twice using a counter variable. Nested loops run an inner loop fully for each iteration of the outer loop. An example nested loop would print a message 200 times. Loops must ensure the condition will become false to avoid an infinite loop.