Nearly all software developers know that software is covered by copyright. Many know that copyright covers the expression of an idea fixed in a medium (such as a series of bytes), and that the copyright rules govern the copying, modifying and distributing of the work. However, only a very few have considered the questions that arise when trying to determine if one work infringes the copyright of another.
Indeed, in the world of software freedom, copyright is seen as a system we have little choice but to tolerate. Many Free Software developers dislike the copyright system we have, so it is little surprise that developers want to spend minimal time thinking about it. Nevertheless, the copyright system is the foremost legal framework that governs software1, and we have to live within it for the moment.