Transport modelling is a fascinating subject, but is often a black art to those who use its results in practice. It is generally regarded as a specialist subject for a few dedicated specialists, and yet more and more planners require transport modelling results in their evidence base for decision-making, whilst also substantial financial investments rely on model outcomes. A better understanding of what transport models are, what they can and cannot do, good practice, and guidance on what matters most in their application, can help these practitioners in their communication with modellers, and ultimately deliver greater value. How do I design a model that suits the questions that need answering and the data I have available? Which questions do I need to ask the modeller to ensure that the model meets my purpose? What assumptions are being made, implicitly or explicitly, and do they matter? How do I check the data inputs in a sensible manner? How do I maintain a model over time? This book is for undergraduate and graduate students, early career professionals and those who need to engage with transport modellers. It is a practical book, although well grounded in the theory. The coverage is accessible and also well referenced to good quality material in other applications.