I would like to thank my co-workers in Gamekit, Docplanner, and Apreel. I especially want to thank my supervisors, who were not only supportive, but who are also a constant source of knowledge and inspiration: Mateusz Mikulski, Krzyysztof Wolniak, Bartek Wilczynski, and Rafal Trzeciak.

I would like to thank Marek Kaminski, Gleb Smirnov, Jacek Jablonski, and Maciej Gorski for the corrections, and Dariusz Bacinski and James Shvarts for reviewing the code of the example application.

I would like to thank my family and my girlfriend - Maja Markiewicz - for their support and help. I especially want to thank them for making an environment that supports passion and self-realization.

I would like to thank the amazing team at Babylon, who are not only professionals but also inspiring and very helpful people, especially Mikolaj Leszczynski, Sakis Kaliakoudas, Simon Attard, Balachandar Kolathur Mani, Sergio Carabantes, Joao Alves, Tomas Navickas, Mario Sanoguera, and Sebastien Rouif.

I offer thanks to all the reviewers, especially technical reviewer Stepan Goncharov, Mikhail Glukhikh, and my colleagues who gave us feedback on the drafts, especially Michał Jankowski.

I am also thankful to my family for all of their love and support. I'd like to thank my parents for allowing me to follow my ambitions throughout my childhood and for my education.

Thanks also go to JetBrains for creating this awesome language and to the Kotlin community for sharing knowledge and being helpful, open, and inspiring. This book could not have been written without you!

I offer special thanks to my friends, especially Konrad Hamela, Marcin Sobolski, Maciej Gierasimiuk, Rafal Cupial, Michal Mazur, and Edyta Skiba for their friendship, inspiration, and continuous support. I value your advice immensely.