What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?

What does ArrayIndexOutOfBoundsException mean and how do I get rid of it?

Here is a code sample that triggers the exception:

String[] names = { "tom", "bob", "harry" };
for (int i = 0; i <= names.length; i++) {
    System.out.println(names[i]);
}