REUSE is an initiative by the Free Software Foundation Europe that proposes a simple, standardised way to license your code. By including the licenses and adding a small licensing header to every file, you can unambiguously declare the licensing situation of your entire project. Because the headers are standardised, you can use tools to automate the creation of headers, verify coverage, highlight any errors, provide a complete summary in the form of a bill of materials. This talk details how it works and why it is important.