A database is a system that stores, organizes, and retrieves structured data efficiently. Applications rely on databases to persist information such as users, orders, or logs. Databases provide querying capabilities so programs can look up records quickly and reliably. Relational databases organize data into tables, while NoSQL databases store documents, key value entries, or graphs. Most backend systems interact with their primary database on nearly every request. Good database design reduces redundancy, improves performance, and ensures data integrity. The choice of database can strongly influence scalability, storage cost, and development complexity. Databases are typically accessed through drivers or ORMs from backend code.
how it works
A relational database uses schemas, tables, and indexes to store and query data. When an application sends a query, the database parses it, generates an execution plan, and then retrieves data using storage engines and memory buffers. Indexes improve performance by letting the database locate rows quickly instead of scanning entire tables. Databases often run on dedicated servers or managed cloud storage services. Transaction features ensure that operations either fully complete or roll back on failure. Monitoring database performance helps identify bottlenecks, slow queries, and contention.