In software, we often talk about user requirements and system requirements. Most people know the terms: users give you user requirements, designers work from system requirements. The terms have entered our lingua franca. However, in my experience, people - stakeholders, analysts, and designers - often fail to differentiate the roles of these two kinds of requirements. Unfortunately, treating user and system requirements as the same thing can create problems for projects. In this column I unpack some problems I've observed with user requirements and system requirements and explore what we can do about them.