Saving your files on someone else's computers via the internet instead of on your device. Like a safety deposit box for data.
Google Drive, Dropbox, and iCloud let you access your photos and documents from any device.
These are all object storage services for storing and retrieving files over the internet via APIs/SDKs and consoles. They are highly durable, scalable, and commonly used for backups, media, data lakes, and static website assets. Differences are mainly in pricing, regions, storage classes/tiers, and ecosystem integrations.