Fink is a project that provides a distribution of open source UNIX tools for Darwin/Mac OS X. It installs packages in /sw to avoid conflicts with the operating system files. Fink downloads source code over the internet which it then compiles and packages locally. It uses the 'fink build' and 'fink install' commands to manage building and installing packages and their dependencies in a coherent way. Fink packages contain the necessary files and configuration to install UNIX tools and their libraries while avoiding conflicts with the operating system.