Writing correct concurrent code is traditionally considered difficult. This is not only because of it being difficult, but also because many programming languages make it more difficult than it should be. Some languages make it too cumbersome, while others make it inflexible, reducing its usability. With that in mind, the Kotlin team tried to make concurrency as simple as possible while still making it flexible enough so that it can be adjusted to many different use cases. Later in the book, we will cover many of those use cases and will use many of the primitives that the Kotlin team has created, but for now let's take a look at common challenges presented when programming concurrent code.

As you can probably guess by now, most of the time it comes down to being able to synchronize and communicate our concurrent code so that changes in the flow of execution don't affect the operation of our application.