Jeroen Janssens is a Senior Machine Learning Engineer at Xomnia in Amsterdam, where he uses Polars on a daily basis. He enjoys wrangling data, implementing machine learning models, and building solutions using Python, R, JavaScript, and Bash. Previously, he ran Data Science Workshops, a training and coaching firm. Jeroen is the author of Data Science at the Command Line (O'Reilly, 2021). He has been an assistant professor at Jheronimus Academy of Data Science and a data scientist at various startups in New York City. Jeroen holds a PhD in machine learning from Tilburg University and an MSc in artificial intelligence from Maastricht University. He lives with his wife and two kids in Rotterdam, the Netherlands. Thijs Nieuwdorp is the Lead Data Scientist at Xomnia in Amsterdam. His interest in the interaction between human and computer led him to an education in Artificial Intelligence at the Radboud University, after which he dove straight into the field of Data Science. At Xomnia he witnessed the birth of Polars as Ritchie Vink started working on it during his employment there, and has been using it in his projects ever since. He enjoys figuring out complex data problems, optimizing existing solutions, and putting them to good use by implementing them into business processes. Outside work Thijs enjoys exploring our world through hiking and traveling, and exploring other worlds through books, games, and movies. He lives in Amsterdam with his partner.