Regarding source folder hierarchy, there are always some common features, such as the src, doc or test folders, which have rather easy-to-understand contents. However, I realized that big projects have both a lib and vendor folders, while I had always thought they were the same, as their names hint at including “third-party libraries from external vendors”. Though, seeing both in the same project
![What is the difference between the "lib" and "vendor" folders?](https://cdn-ak-scissors.b.st-hatena.com/image/square/3c437216209db3b0103c3276a08ac33ec3c0a00c/height=288;version=1;width=512/https%3A%2F%2Fcdn.sstatic.net%2FSites%2Fsoftwareengineering%2FImg%2Fapple-touch-icon%402.png%3Fv%3D1ef7363febba)