Concatenation describes the operation of joining two strings together. In Java, the operator "+" normally acts as an arithmetic operator unless one of its operands is a String. If necessary it converts the other operand to a String before joining the second operand to the end of the first operand.
To join the two Strings "pan" and "handle":
System.out.println("pan" + "handle");
If one of the operands is not a String it will be converted:
int age = 12; System.out.println("My age is " + age);
There is also a method called concat defined in the String class that performs the same operation: