As web developers, we all end up coming in contact with software we didn't write, be it to use in our own projects or to modify in some way to satisfy a need for ourselves or a client. We might even be distrubuting a library or an application. What we may not realize is that licensing is a very important idea which guides what we can and cannot use in our own software. We'll navigate the murky waters of Open Source Licensing and copyright as it relates to developers.