"A gentle introduction to Python" is a lecturing book aimed at a non-specialist audience willing to learn the fundamentals of the language. It also serves as a first contact with programming for those readers with no previous experience in this task. The book features a theoretical review of each aspect of the core of the language, supported by more than 180 exercises along with over100 examples and solutions of the use of the Python scripts. Therefore, it serves as an introductory guide to help those interested to get successfully started with Python programming language. The target audience for this book are first-year students in STEM. In this regard, it has been tailored according to the needs in different degree and master programmes offered at the Public University of Navarre (Universidad Pública de Navarra). Nevertheless, this work is not restricted to students, since the examples and exercises across the book have been used, and refined, by different professional audiences interested in programming. Hence, this work can be of use for a transversal audience, from the general public to a higher education context, which will be provided with an insight into the bases of the Python programming language and its possible applications.