Walter L. Hurley is Professor Emeritus in the Department of Animal Sciences at the University of Illinois in Urbana, Illinois, USA. His research focuses on a broad range of topics related to the biology of lactation. His studies examine aspects of comparative milk composition, immunoglobulin transport through colostrum, lactation physiology, and mammary gland development, function, and involution in cattle and swine. He has published over 100 peer-reviewed research papers, reviews and book chapters. He has been the recipient of many recognitions for his teaching, and has shared his experience and knowledge of the concepts of teaching and learning with many national and international audiences. His online, open-access Lactation Biology course (Coursera, Lactation Biology) includes more than 120 short videos, offering learners fundamental information about the biology of lactation.