What is meant by “managed” vs “unmanaged” resources in .NET?

Question

What is meant by the terms managed resource and unmanaged resource in .NET? How do they come into the picture?

Answer 1

The term "unmanaged resource" is usually used to describe something not directly under the control of the garbage collector. For example, if you open a connection to a database server this will use resources on the server (for maintaining the connection) and possibly other non-.net resources on the client machine, if the provider isn't written entirely in managed code.

This is why, for something like a database connection, it's recommended you write your code thusly:

using (var connection = new SqlConnection("connection_string_here"))
{
    // Code to use connection here
}

As this ensures that .Dispose() is called on the connection object, ensuring that any unmanaged resources are cleaned up.