What is a "receiver" in Kotlin and why is it needed?

Hello colleagues! I just started learning Kotlin after Java and came across the term "receiver". I'm reading the documentation and see things like `apply`, `let`, `run`, `with` — and everywhere they write about receivers. But I can't fully understand what it is and how it works.\n\nHere's a simple example. I write this code:\n\n```kotlin\ndata class Person(var name: String = "", var age: Int = 0)\n\nfun main() {\n val person = Person().apply {\n name = "Alice" // Here I access name directly, without person.name\n age = 30\n }\n println(person)\n}\n```\n\nI understand that inside the `apply` block I can write `name = "Alice"` instead of `person.name = "Alice"`. But how does it work? What does "function with receiver" mean? Is it some kind of magic closure? Or is it similar to how