Usability engineers plan and execute usability studies, task analyses, heuristic evaluations, and accessibility assessments. They examine cognitive load, efficiency, error rates, and user satisfaction across digital systems. They collaborate with product teams to refine designs and ensure interfaces meet usability, accessibility, and compliance standards (WCAG, ISO usability guidelines). They work across software, healthcare systems, industrial systems, transportation interfaces, and consumer technologies. As organisations prioritise accessible, user-friendly solutions, usability engineering plays a vital role in ensuring high-quality user experiences worldwide.