Assembly Location

To understand where assemblies are located, you must consider that they are generally divided into private assemblies and shared assemblies. Private assemblies are standalone assemblies or assemblies that reside exclusively in the same folder of the application that holds a reference. This is a common scenario, because it makes the deployment easier because you just need to distribute the content of the application folder (known as XCopy mode). Every application holding a reference to a private assembly needs to have a copy of the assembly inside its folder. This means that if you have ten applications referencing the assembly, you will also have ten copies of the assembly. Shared assemblies are instead files with a digital signature that can be installed to a particular location known as the Global Assembly Cache that allows having a single shared copy of the assembly only if this comes from a trusted publisher. The Global Assembly Cache is an important topic that Chapter 53, “Understanding the Global Assembly Cache,” addresses, so read it for further details.