The advantage of making the string type immutable is that you can do what's known as "string interning": if the same string shows up multiple times in your prog

The advantage of making the string type immutable is that you can do what's known as "string interning": if the same string shows up multiple times in your program, only one copy has to be kept in memory. This is particularly useful for compile-time constant strings. C and C++ actually do a similar thing with their string literals, which are immutable even though normal strings aren't.