First of all, NDepend is a static analysis tool for .NET that can be integrated into Visual Studio (as an extension) or used as part of your continuous delivery pipeline. It allows you to keep track of code quality, technical dept, and visualize the dependencies to get a better overview of the codebase.
A long, long time ago, developers were using machine codes to program computers. It was hard to keep all of them in mind, easy to make a mistake, and almost impossible to read. After struggling with machine codes, they created mnemonic codes to refer to machine code instructions aka Assembly language. The assembler was responsible for translating assembly language to machine codes.