2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/213597Precision studies of QCD at $e^+e^-$ colliders are based on measurements of event shapes and jet rates. To match the high experimental accuracy, theoretical predictions to next-to-next-to-leading order (NNLO) in QCD are needed for a reliable interpretation of the data. We report the first calculation of NNLO corrections (${\cal O}(α_s^3)$) to three-jet production and related event shapes, and discuss their phenomenological impact.5 pages, LaTeX, to appear in the proceedings of the International Linear Collider Workshop LCWS07, Hamburg, 2007High Energy Physics - Phenomenologytext