C#..(Walk through C# 2008 / 2010)

C# is a new programming language designed to work with .NET Framework. C# 2008 works on .net frame work 3.5. and 2010 for framework 4.0

What is .NET Framework?

.Net Framework can be mentioned as a type safe environment for executing assemblies. The word type safe stands for type( string,int,date,uint) etc are safe here and can cast values to specific cast only.
eg: int i=20; and int i="data" is wrong and against type safe which will throw compile time errors.

where as Php is not a type safe ..
eg: $data=10; and also $data="hai" acceptable in php.

Building blocks of .Net

CLR (Common Language run time )
CTS (Common Type System)
CLS (Common Language Specification)

Primary role of CLR is to locate , load and manage .NET types. Also CLR performs threading handling, Memory management, Security checks etc.

CTS the another building block describes all possible data types. CTS also sepcifies different entities can interact each other.

CLS specifies the subset of common languages and common types that can be agreed in between.

Code compilation in .NET

So as mentioned above the IL (Intermediate Language is going to run on .NET framework)
Compilers will be different for different programming languanges.