Introduction to .NET framework
The .net framework is an infrastructure that is used to:
- Build, deploy, and run different types of applications and services using .net technologies.
- Minimize software development, deployment, and versioning conflicts.

With improvements in networking technology:
- Distributed computing has provided the most effective use of processing power of both client and server processors.
- Applications became platform-independent with the emergence of Internet, which ensured that they could be run on PCs with different hardware and software combination.
- Communication with each other has become possible for the clients and servers in a vendor-independent manner.

The following figure shows the different features accompanying the transformation in computing, Internet, and application development:

Transformation in Computing ----> Grouping Web Server.
Transformation in the Internet ----> Receiving data in HTML code | Enabling communication in vendor-independent manner.
Transformation in Application Development ----> Application used anywhere and by anyone.


All the transformations are supported by the technology platform introduced by Microsoft called as .NET framework.
Data stored using the .NET Framework is accessible to a user from any place, at any time, through any .NET compatible device.
The .NET Framework:
- Is a programming platform that is used for developing Windows, Web-based and mobile software.
- Has a number of pre-coded solutions that manage the execution of programs written specifically for the framework.
- Is based on two basic technologies for communication of data:
  - eXtensible Markup Language (XML)
  - The suite of Internet protocols.

Following are the key features of XML:
- It separates actual data from presentation.
- It unlocks information that can be organized, programmed, and edited.
- It allows Web sites to collaborate and provide groups of Web services. Thus, they can interact with each other.
- It provides a way for data to be distributed to a variety of devices.

Apart from XML, the .NET platform is also built on Internet protocols such as:
- Hypertext Transfer Protocol (HTTP)
- Open Data Protocol (OData)
- Simple Object Access Protocol (SOAP)

In traditional Windows applications:
- Codes were directly compiled into the executable native code of the operating system.

Using the .NET Framework:
- The code of a program is compiled into CIL (formerly called MSIL) and stored in a file called assembly.
- This assembly is then compiled by the CLR to the native code at run-time.

The following figure represents the process of conversion of CIL code to the native code:

.NET code          ----> CIL code ----> Compiled into native code ----> Execution of code
   |
.Net class library


TIPS:
CIL - Common Intermediate Language.
CLR - Common Language Runtime.

The CLR provides many features such as:
- Memory management
- Code execution
- Error Handling
- Code safety verification
- Garbage collection

The applications that run under the CLR are called managed code.

Microsoft has released different versions of the .NET framework to include additional capabilities and functionalities with every newer version.

Following are the versions of the .NET Framework:

.NET Framework 1.0
.NET Framework 1.1
.NET Framework 2.0
.NET Framework 3.0
.NET Framework 3.5
.NET Framework 4.0
.NET Framework 4.5

The following table shows various versions of .NET Framework and Visual Studio:

Year   .NET Framework    Distributed with OS        IDE Name
2002        1.0                                              Visual Studio .NET (2002)
2003        1.1          Windows Server 2003                 Visual Studio .NET (2003)
2005        2.0                                              Visual Studio .NET (2005)
2006        3.0          Windows Vista,                      Visual Studio .NET (2005)
                         Windows Server 2008
2007        3.5          Windows 7,                          Visual Studio .NET (2008)
                         Windows Server 2008 R2
2010        4.0                                              Visual Studio .NET (2010)
2012        4.5          Windows 8,                          Visual Studio .NET (2012)
                         Windows Server 2012