What happens if a network request is executed in the main thread of the program?

Performing a network request on the main (UI) thread of an Android application will lead to blocking the user interface until the request completes. As a result, the application will stop responding to user actions, which can cause an ANR (Application Not Responding) — a system warning about freezing.

Therefore, network operations should be performed in a background thread, for example, using AsyncTask, Thread, Coroutine, or libraries like Retrofit that support asynchrony.

Example with Kotlin Coroutine:

GlobalScope.launch(Dispatchers.Main) {
    val result = withContext(Dispatchers.IO) {
        // network request
    }
    // update UI with the result
}