The java.io.IOException is a checked exception in Java that occurs during Input/Output (I/O) operations, often caused by issues such as a missing file, permission problems, or unexpected disruptions. Being a checked exception, it requires explicit handling either through try-catch blocks or by declaring it in a method's throws clause. An example is provided where an IOException is thrown when attempting to read a non-existent file, demonstrating the importance of checking for file existence before performing I/O operations. Solutions to fix IOException include verifying file presence, ensuring appropriate permissions, implementing retry mechanisms for network I/O, and employing robust error handling with logging. The text also highlights the use of Rollbar for real-time error tracking and management, aiding in the confident deployment of production code.