About the Authors: Roman Elizarov is a Project Lead for Kotlin at JetBrains and currently focuses on the Kotlin language design in the role of Lead Language Designer. Roman Elizarov previously designed and developed high-performance trading software for leading brokerage firms and market data delivery services that routinely handle millions of events per second. He has been working on Kotlin at JetBrains since 2016 and has contributed to the design of Kotlin coroutines and the development of the Kotlin coroutines library. Svetlana Isakova began as a member of the Kotlin compiler team and is now a developer advocate for JetBrains. She teaches Kotlin and speaks at conferences worldwide. She is a co-creator of the course "Kotlin for Java developers" at Coursera and is a co-author of the book "Atomic Kotlin." As a Kotlin Developer Advocate at JetBrains, Sebastian Aigner spends a lot of time thinking about how technologies can empower and delight people. When he first tried Kotlin, it was love at first sight.He gave talks at KotlinConf, participated in the Kotlin/Everywhere campaign, and spoke at a multitude of other conferences. He hosts the Talking Kotlin podcast together with Hadi Hariri, and creates videos for the official Kotlin YouTube channel. Dmitry Jemerov has been working with JetBrains since 2003. He was one of the initial developers working on Kotlin as the project was started, and he's deeply familiar with the design of the language and the reasons for the decisions that were made during its development. He's currently responsible for Kotlin documentation.