What are the advantages of using Threads ?

One of the most compelling reasons for threads is to produce a responsive user interface. Consider a program that performs some CPU-intensive operation and thus ends up ignoring user input and being unresponsive. The basic problem is that the program needs to continue performing its operations, and at the same time it needs to return control to the user interface so that the program can respond to the user. If you have a “quit” button, you don’t want to be forced to poll it in every piece of code you write in your program, and yet you want the quit button to be responsive, as if you were checking it regularly.
Threading can reduce computing efficiency somewhat in single-CPU machines, but the net improvement in program design, resource balancing, and user convenience is often quite valuable. In general, threads enable you to create a more loosely-coupled design; otherwise, parts of your code would be forced to pay explicit attention to tasks that would normally be handled by threads.