The document discusses the implementation of client-side encryption in MongoDB 4.2, highlighting how sensitive data is encrypted before being sent to the database and decrypted upon retrieval. It contrasts this method with other encryption strategies, such as encryption-at-rest and encryption-in-transit, emphasizing the protection of data integrity and confidentiality. Additionally, the document details key management strategies, schema validation, and the handling of sensitive information to comply with data protection regulations like GDPR.