(Common Language Runtime) The runtime engine in Microsoft's .NET platform. The CLR compiles and executes programs in Microsoft Intermediate Language (MSIL). The counterpart to the CLR for the Common Language Infrastructure (CLI), ECMA's standard version of .NET, is the Virtual Execution System (VES).

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.