 As we noted in the very beginning of this entry, one of the two key tasks for the notion of fundamentality is to capture the idea that there is a foundation of being and that everything else depends on the fundamental entities. This idea about fundamentality is often expressed in terms of well-foundedness (Morganti 2009: 272; Orilia 2009: 333; Fine 2010: 100; Schaffer 2010a: 37; Bennett 2011a: 30; Bliss 2013: 416; Trogdon 2013: 108; Tahko 2014: 260; Raven 2016: 614; Bohn 2018; Jago 2018). But the notion of well-foundedness itself is sometimes used without much further qualification, and there are many instances where another term is used instead for what is clearly the same general idea (e.g., Lowe 1998: 158; R. Cameron 2008; Paseau 2010; Rosen 2010). A common formulation of this general idea is as follows: a priority/dependence chain is well-founded if and only if it terminates, i.e., has an end constituted by one or more entities that do not depend on any other entity. But not all the above-mentioned authors would be happy with this particular formulation, and it turns out that sometimes philosophers may even have talked past each other due to having slightly different formulations of well-foundedness in mind. Fortunately, the literature has matured, and we now have a number of much more precise accounts of the various potential formulations of well-foundedness (see especially Dixon 2016; Rabin &amp; Rabern 2016; Litland 2016b; Wigglesworth 2018).