Usability Heuristics are a set of values or principles that designers use and follow to optimise the user experience (UX). For example, Usability Heuristics help designers create a website that is user-friendly in terms of navigation, visibility, error aversion, aesthetics, flexibility, efficiency, etc.
After the initial design is complete, a heuristic evaluation should be conducted in order to identity any components of a design that aren’t user-friendly and could hamper customer satisfaction and conversion rates. After the evaluation, tweaks and improvements can be made to optimise UX.