What is the main categories in databases?

The main categories of databases include relational databases, which use structured query language (SQL) to manage data in tables with predefined relationships; NoSQL databases, which are designed for unstructured or semi-structured data and offer flexibility in data models; object-oriented databases, which store data in the form of objects as used in object-oriented programming; and graph databases, which focus on the relationships between data points. Each category serves different use cases and data management needs.