Cloud storage is the technology which allows users to store data online at one place for some consideration in the form of subscription fees. This has allowed users to store unfathomable amounts of data on a single platform, eliminating the problem of maintaining multiple hardware storage devices.
However, every technology has its drawbacks
The major drawback of cloud storage is security of data. Since data is stored in just one centralized server any threat or attack can lead to the compromisation of data.
Blockchain solves this problem by distributing the data across a decentralized network so even if data on one node is erased it can still be traced. Another thing to learn is that the data cannot be accessed by everyone. This is ensured through public and private keys. Blockchain simply ensures that there are multiple copies of the data thus also ensuring that data cannot be tampered with.