ANR errors, also known as Application Not Responding errors, occur when an app becomes unresponsive to user input for more than five seconds or when a broadcast receiver is unable to finish executing its `onReceive()` method within 10 seconds. This can lead to frustration and abandonment of the app by users. ANRs are often overlooked but can have a significant impact on user experience. Developers can use crash reporting tools with ANR detection, such as Instabug Crash Reporting, to capture these errors and identify the root cause. To avoid ANRs, developers should consider strategies like running slow code on worker threads, executing I/O operations on worker threads, mismanaging lock states, avoiding deadlocks, and optimizing broadcast receivers. By addressing these causes, developers can improve their app's stability and user experience.