Language interoperability is the capability of two different programming languages to natively interact as part of the same system and operate on the same kind of data structures.

There are many ways programming languages are interoperable with one another. HTML, CSS, and JavaScript are interoperable as they are used in tandem in webpages. Some object oriented languages are interoperable thanks to their shared hosting virtual machine (e.g. .NET CLI compliant languages in the Common Language Runtime and JVM compliant languages in the Java Virtual Machine).