Recursion is a technique in Java where a method calls itself directly or indirectly. It is used to break down complicated problems into simpler ones, making it easier to solve them. Recursion can be difficult to understand, but experimenting with it can help to figure out how it works.

In Java, a recursive method is a method that calls itself. Recursion works by representing a problem in terms of one or more smaller sub-problems and adding base conditions that stop the recursion. For example, the factorial of a number can be computed by knowing the factorial of the number minus one.

Recursion can be used to solve a variety of problems in Java, such as adding a range of numbers together, computing the Fibonacci series, and checking if a string is a palindrome. However, it is important to be careful when using recursion, as an excessive number of recursive callbacks can trigger a StackOverflowError.