The extremes of foot posture (e.g., frank pes planus and pes cavus) are easily recognizable clinically and without recourse to sophisticated technology, but such foot evaluations undertaken subjectively are often criticized for a lack of subtlety. Where pathology is accompanied by clear neurological and histological change, even subjective classifications have good face validity. Consequently, simple dichotomous clinical classifications are in common use, with most descriptors indicating simply whether “pathology” is present or absent. Such discrete classifications (for instance, “cavus” versus “normal” or “pes planus”) are consequently used widely (Figure 4.1; Redmond, 2012).