I currently reading a book “Modern Concurrency on Apple Platforms”.

The book uses the term “Concurrent Context” many times without actually explaining the context of such an context.

For example: “Task has got an initalizer with a closure, which itself is concurrent context”.
Or: “What happens if you don’t have a concurrent context? Somewhere up ith the call hierarchy, you will find a situation in which there is no concurrent context at all, to run the code in.”

Can someone explain the term “Concurrent Context” in an easy to get way?

Searched the web and read in the mentioned book.