The IsNested property returns true for all nested types, regardless of visibility. To test for nesting and visibility at the same time, use the related properties IsNestedAssembly, IsNestedFamily, IsNestedFamANDAssem, IsNestedFamORAssem, IsNestedPrivate, or IsNestedPublic.

Note
The VisibilityMask enumeration member selects the visibility attributes for a type.

The following code example displays the value of the IsNested property for both a protected nested class and a public nested class.

using System;

public class Example
{
    protected class NestedProtected
    {
    }

    public class NestedPublic
    {
    }

    public static void Main()
    {
        Type t = typeof(NestedProtected);
        Console.WriteLine("Is {0} nested? {1}", t.FullName, t.IsNested);
        t = typeof(NestedPublic);
        Console.WriteLine("Is {0} nested? {1}", t.FullName, t.IsNested);
    }
}

/* This example produces the following output:

Is Example+NestedProtected nested? True
Is Example+NestedPublic nested? True 
 */

.NET Framework

.NET Framework Client Profile

Portable Class Library

Windows 8 Release Preview, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 SP2, Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference