Common Language Runtime is one of the main building blocks of Microsoft .NET Framework which is responsible for performing various operations under .NET Framework.
When you design the application using Microsoft .NET languages like C#.NET or VB.NET, the language has its own complier which compiles the code into common format that is CIL [Common Intermediate Language]. Then CIL gets targeted to CLR which in turn performs many operations. It converts CIL into Native code with the help of JIT.
CLR also performs various other operations like Memory Management, Application Execution, Thread Management, Security checks, load the required assemblies and their types. The code which is managed by CLR is also known as Managed Code. All the managed languages are handled by a single runtime that is CLR.
Common Type System (CTS) defines how the types are defined and used in the Common Language Runtime. CTS provides cross-language integration, type safety, and high-performance code execution. The Common Type System for language integration works as follows -
When you define an integer variable in VB.NET and declare integer in C#.NET, both the languages share the same type which is Int32, available under .NET Framework.
CTS defines rules which must be followed by languages in order to make objects written in one language callable in other languages.
Microsoft .NET Framework provides various primitive data types which can be used while developing applications using various languages.
Common Language Specification (CLS) is a set of rules. CLS rules also define a subset of CTS. By defining components using CLS features only, developers are guaranteed to make use of these components in all the other languages which are CLS compliant languages. Most of the types which are defined under .NET framework are CLS complaint.
