You can prevent a class from overriding in C# by using the sealed keyword; whereas, the NotInheritable keyword is used to prevent a class from overriding in Visual Basic.

When a class is derived from another class, then the members of the base class become the members of the derived class. The access modifier used while accessing members of the base class specifies the access status of the base class members inside the derived class.

The syntax to inherit a class from another class in C# is as follows:
class MyNewClass : MyBaseclass

.NET does not support multiple inheritance directly because in .NET, a class cannot inherit from more than one class. .NET supports multiple inheritance through interfaces.

The System.Collections namespace contains all the collection classes.

The JIT compiler is an important element of CLR, which loads MSIL on target machines for execution. The MSIL is stored in .NET assemblies after the developer has compiled the code written in any .NET-compliant programming language, such as Visual Basic and C#.

JIT compiler translates the MSIL code of an assembly and uses the CPU architecture of the target machine to execute a .NET application. It also stores the resulting native code so that it is accessible for subsequent calls. If a code executing on a target machine calls a non-native method, the JIT compiler converts the MSIL of that method into native code. JIT compiler also enforces type-safety in runtime environment of .NET Framework. It checks for the values that are passed to parameters of any method.

For example, the JIT compiler detects any event, if a user tries to assign a 32-bit value to a parameter that can only accept 8-bit value.

.NET Framework provides enormous advantages to software developers in comparison to the advantages provided by other platforms. Microsoft has united various modern as well as existing technologies of software development in .NET Framework. These technologies are used by developers to develop highly efficient applications for modern as well as future business needs. The following are the key components of .NET Framework:

 =>   .NET Framework Class Library
 =>   Common Language Runtime
 =>   Dynamic Language Runtimes (DLR)
 =>   Application Domains
 =>   Runtime Host
 =>   Common Type System
 =>   Metadata and Self-Describing Components
 =>   Cross-Language Interoperability
 =>  .NET Framework Security
 =>   Profiling
 =>   Side-by-Side Execution

.NET Framework is a complete environment that allows developers to develop, run, and deploy the following applications:

 => Console applications
 => Windows Forms applications
 => Windows Presentation Foundation (WPF) applications
 => Web applications (ASP.NET applications)
 => Web services
 => Windows services
 => Service-oriented applications using Windows Communication Foundation (WCF)
 => Workflow-enabled applications using Windows Workflow Foundation (WF)

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