grokking concurrency!
It's okay if you don't know complex formulas and technical terms!
You can understand concurrency just by reading it!

Concurrency is a method of processing programs simultaneously by separating them into independent executions. To implement this, you need to know various technologies and concepts such as complexity, parallelism, threads, processes, multitasking, and coroutines and know how to use them appropriately.
This book explains the often-difficult concept of simultaneity through real-life examples and engaging illustrations.
It does not limit itself to a specific programming language or implementation, but rather helps you learn more fundamental concepts and principles.
In particular, concepts are explained easily with visual diagrams rather than complex formulas to ensure clear understanding, and various stories are used to attract the reader's interest.
After reading this book, you will have a complete picture of concurrency.

I, too, have been caught in this fascinating web.
It was in this web that I first encountered the words concurrency and asynchrony.
It felt like I had found a hidden treasure.
It is a wild and powerful force that is difficult to handle, and if properly tamed, it can transform an ordinary program into a very powerful program.
But this treasure can only be unlocked by solving various puzzles scattered across the technological landscape: complexity, concurrency and parallelism, threads, processes, multitasking, and coroutines.
As I studied these concepts, I longed for someone who could help me understand the big picture, or someone who could teach me.
However, I have yet to find any material that can bridge the gap between theory and practice, and between each programming language, so I decided to write it myself.
This book was born against this backdrop.
It will be your guide to illuminate the path you must take in this complex maze.

This book is not suitable as an all-encompassing reference book.
Rather, it is a book that is fun to read, weaving together various stories and cultural references.
Originally planned as a theoretical guide, it evolved into its current format, featuring a variety of stories, cultural references (count them!), and interesting illustrations.
The quirky humor that reveals my love of dumplings and pizza is a bonus.
Learning parallelism doesn't have to be boring, right?

Let's unravel the mysteries of concurrency and asynchrony together with this book.
Starting from the basics of concurrency, you will learn how to use Python's cool features async and await, and the practical training will focus on Python.
It's okay if you're not fluent in Python.
The concepts and techniques we will learn are not limited to any particular language implementation.

Still, some readers may wonder, 'Why Python?'
Because Python is a language that has a perfect balance of expressiveness and simplicity.
This allows us to focus on mastering concurrency without being distracted by other factors.
And it's also my preferred language.

This book will be helpful to both experienced developers seeking a deeper understanding of concurrent systems and beginners interested in concurrency theory.
Through this book, you will not only understand the secrets of concurrency, but also gain the ability to build scalable, efficient, and resilient software systems.

It's time to embark on a journey where the program dances like an octopus, crossing the blurred boundaries of time and space.
I didn't mishear.
That's the octopus you know.
Octopuses swim in the deep sea, using their eight tentacles in perfect harmony.
It is the perfect animal to symbolize a complex yet beautiful simultaneous system.
Well then, let's begin our journey.

--- From the Author's Note