What is using keyword in C#?

using keyword is used Remove unused memory form the object Using(SqlConnection objConn=new SqlConnection()) { }

There are two usage of "using" keyword 1. to import namespaces e.g using System; using System.IO; 2. to handle unmanaged resources An object inside or outside the .NET Framework, which uses external code (For example: file handles, streams, DB connections). The Garbage Collector can't handle unmanaged resources, so we need to release them manually. e.g using (Stream input = File.OpenRead(filename)) { ... } This can only be used with types that implement IDisposable.