I was just wondering how API's can be shared between different Programming languages. I mean, MS have .Net which uses VB.net C# and various other technologies.I doubt .Net is written for each programming language.How are structs and classes shared between languages?Also the same for Unity3D - Javascript shares API's with C# and BOO.How? 
Sharing API's between different Programming languages?
api
They're based on the Common Language Infrastructure, or CLI. It's basically a virtual machine where all of these languages compile to the same bytecode and read out assemblies which are in terms of the CLI. This provides an abstraction over the source and target language.