I&#x27;ve most often seen &quot;systems software&quot; used to designate software whose primary users are other programmers or systems as opposed to end users (e.g. databases, message queues, monitoring tools, etc.).<p>Ruby is typically used for writing business web applications and while those applications run on the back end, their primary users are business&#x2F;end users.<p>Of course, there doesn&#x27;t seem to be a clear consensus on how those terms are used and the line is often blurry between the categories.