Design

Beside having many languages and technologies probably you may wonder why dotnet(.net)? why not something else this chapter may clarify your doubt about why people go for dotnet
The main reason for going to Dotnet is

Interoperability

Because computer systems commonly require interaction between newer and older applications, .NET Framework provides means to access functionality implemented in newer and older programs that execute outside .NET environment. Access to COM components is provided inSystem.Runtime.InteropServices and System.EnterpriseServices namespaces of the framework; access to other functionality is achieved using theP/Invoke feature.

Common Language Runtime engine

Common Language Runtime (CLR) serves as the execution engine of .NET Framework. All .NET programs execute under the supervision of CLR, guaranteeing certain properties and behaviors in the areas of memory management, security, and exception handling.

Language independence

.NET Framework introduces a Common Type System, or CTS. CTS specification defines all possible datatypes and programming constructs supported by CLR and how they may or may not interact with each other conforming to Common Language Infrastructure (CLI) specification. Because of this feature, .NET Framework supports the exchange of types and object instances between libraries and applications written using any conforming .NET language.

Framework Class Library

Framework Class Library (FCL) is a library of functionality available to all languages using .NET Framework. FCL provides classes that encapsulate a number of common functions, including file reading and writing, graphic rendering, database interaction, XML document manipulation, and so on. It consists of classes, interfaces of reusable types that integrates CLR.

Simplified deployment

.NET Framework includes design features and tools which help manage the installation of computer software to ensure that it does not interfere with previously installed software, and that it conforms to security requirements.

Security

The design addresses some of the vulnerabilities, such as buffer overflows, which have been exploited by malicious software. Additionally, .NET provides a common security model for all applications.

Portability

While Microsoft has never implemented the full framework on any system except Microsoft Windows, it has engineered the framework to be platform-agnostic,and cross-platform implementations are available for other operating systems (see Silverlight and § Alternative implementations). Microsoft submitted the specifications for CLI (which includes the core class libraries, CTS, and the Common Intermediate Language), C#,and C++/CLI to both ECMA andISO, making them available as official standards. This makes it possible for third parties to create compatible implementations of the framework and its languages on other platforms.