What is the purpose of applying the 'using' directive in a programming language?

In C#, the using directive serves two main functions:

1. Namespace inclusion — allows using classes and other types from specified namespaces without needing to write the full namespace path.

   For example:

   using System;
   
   class Program {
       static void Main() {
           Console.WriteLine("Hello"); // You can just write Console instead of System.Console
       }
   }
   

2. Resource management — in a using statement, resources implementing the IDisposable interface can be automatically released. This guarantees that the Dispose() method is called after the object is used, which is important for proper memory release, file handles, etc.

   Example:

   using (var file = new StreamReader("file.txt")) {
       string content = file.ReadToEnd();
   } // Here, file.Dispose() is automatically called
   

Thus, using helps write cleaner and safer code.