These libraries are relatively small, focused pieces of code. They are intended to be reused even in commerical applications, which is why most of them have a generous open-sourc license.
In following with Debian conventions, all of the libraries are suffixed with the language or framework they are used in. For example, the CIL libraries end in "-cil" while the Python libraries end in "-python".
Common Intermediate Language
Common Intermediate Language (CIL) is better known as .NET. More common CIL languages are C# and VB.NET, but there are a number of lessor known ones such as F#, Boo, LOLCATS. All of these have a common instruction set which allows use of one CIL library to be used by any other CIL language.