Can you name the main types of data storage systems?

Main types of data storage systems:

• File systems — data is stored as files and folders on disks (e.g., ext4, NTFS).
• Relational databases (SQL) — data is organized into tables with relationships between them (MySQL, PostgreSQL).
• Non-relational databases (NoSQL) — store data as documents, key-value pairs, graphs, or columns (MongoDB, Redis, Cassandra).
• Object storage — data is stored as objects with metadata, often used for large volumes of unstructured data (Amazon S3).
• Block storage — low-level data storage in the form of blocks, used in SAN and virtualization.

The choice depends on requirements for data structure, access speed, and scalability.