What is the purpose of using `or die()` in conjunction with `mysqli_query()` in PHP?

Using `or die()` after `mysqli_query()` is a concise way to handle database query errors. It checks if the query was successful. If the query fails, `mysqli_query()` returns false, which triggers the `or die()` clause. This causes the script to immediately terminate and display an error message, typically indicating the error encountered by the database server. This is crucial for debugging and preventing the execution of code that depends on a failed query.