Can you explain what NoSQL databases are and why they are needed?

NoSQL databases are a type of database management systems that differ from traditional relational databases (SQL) in their data storage and processing structures.

Main features of NoSQL:

• Data is stored in formats other than tables: documents (JSON, BSON), key-value, graphs, or column stores.
• Flexible data schema, allowing easy modifications without complex migrations.
• Well horizontally scalable, which is important for large volumes of data and distributed systems.

Why NoSQL is needed:

• When data does not fit into a strict table structure.
• For applications with high load and scalability requirements.
• For rapid prototyping and changes in data structure.

Example: MongoDB — a document-oriented NoSQL database where data is stored as JSON-like documents.