The 21st International Conference on Microscopy of Semiconducting Materials (MSM-XXI) reports progress in the imaging, diffraction and spectroscopy of inorganic and hybrid perovskite semiconductor nanostructures used in (opto)electronic and photonic devices, as well as interfaces of thin dielectric, metal or polymer films to such semiconductors. With a focus on electron microscopy but also encompassing a wide range of related techniques, such as scanning probe microscopy and 3D atom probe, this series has now been running for 40 years. Speakers: Chris Boothroyd, NTU, Singapore, Catherine Bougerol, CNRS Institut Neel, France, David Cooper, CEA Grenoble, France, George Dimitrakopulous, University of Thessaloniki, Greece, Paola Favia, IMEC, Belgium, Crispin Hetherington, University of Lund, Sweden, Martin Hytch, CEMES Toulouse, France, Hannah Joyce, University of Cambridge, UK, Martina Luysberg, FZ Jülich, Germany, Ian MacLaren, University of Glasgow, UK, Lorenzo Rigutti, Université de Rouen, France, Carol Trager-Cowan, University of Strathclyde, UK, Ichiro Yonenaga, Tohoku University, Japan. Time: 9:30 am to 5:00 pm. Venue details: Fitzwilliam College, Storey's Way, Cambridge, Cambridgeshire, CB3 0DG, United Kingdom.