Web data extraction is frequently and notoriously unreliable, because you must contend with many external factors over which you have no control. A target website may fail because of defects in the web application, or there may be problems with the Internet connectivity anywhere between you and the target website. These problems may seem negligible when you are browsing a few websites with a normal web browser, but a web data extraction agent is capable of navigating more web pages in a few hours than a human can view in an entire year. So, small glitches can become significant problems that inhibit reliable data extraction. You can minimize these factors with error handling, especially for your critical web data extraction tasks.