Data loss can occur due to various reasons, such as accidental deletion, hardware failure, malware infection, theft, or unauthorized access. Data classification procedures can help to identify and protect sensitive data, but they are not sufficient to prevent data loss. The most effective way to protect against data loss is to conduct periodic security awareness training for employees, which can educate them on the importance of data security, the best practices for data handling and storage, and the common threats and risks to data.