WhatsApp introduced end-to-end encrypted backups in 2021. The feature was announced in September and began rolling out to Android and iOS users in October, extending WhatsApp's end-to-end encryption beyond live conversations to stored chat backups.
Before this option existed, backups saved in services such as Google Drive or Apple iCloud were not protected by WhatsApp's own end-to-end encryption in the same way as messages exchanged inside the app. With encrypted backups enabled, neither WhatsApp nor the cloud-storage provider can read the backup contents.
The protection is optional and requires the user to create either a password or a unique 64-digit encryption key. WhatsApp cannot recover the backup if the user loses both the password or key and access to the account. This is why encrypted backups are distinct from WhatsApp's original message encryption, which was rolled out for chats in 2016.