Definition of: CLR

(Common Language Runtime) The runtime engine in Microsoft's .NET platform. The CLR compiles and executes programs in Microsoft Intermediate Language (MSIL). The ECMA European standards organization has its own version of the .NET platform, and the CLR counterpart is called the "Virtual Execution System" (VES). See CLI.

Common Rules and Types
The CLR and VES include the Common Language System (CLS), which sets the rules and regulations for language syntax and semantics, as well as the Common Type System (CTS), which defines the data types that can be used. Because all programs use the common services in the CLR, no matter which language they were written in, such applications are said to use "managed code."

Common Services
The CLR and VES runtime engines are similar to the Java Virtual Machine (JVM). They provide a fundamental set of services that all programs use. The difference is that Java bytecode can also be interpreted as well as compiled, but the JVM supports only Java, not multiple programming languages. See .NET Framework.