The N+1 query problem occurs when a database-driven application executes multiple queries in a loop, leading to slower performance due to the overhead of repeated database connections and data retrieval. This can happen when an app fetches a list of records, then loops through each record to retrieve additional related data, resulting in many small queries instead of one large, optimized query. To solve this issue, developers should aim to use JOIN statements or other optimization techniques to reduce the number of queries and improve performance. By identifying N+1 queries and refactoring code to use more efficient database interactions, developers can significantly improve their app's load times and overall performance. Additionally, tools like Laravel Debug Bar and PlanetScale Insights can help detect and diagnose performance issues, including N+1 queries.