A columnar database uses a structure that allows for rapid querying by organizing data in columns rather than rows, facilitating efficient data retrieval for analytical queries. This design is particularly advantageous for read-heavy operations, where quick access to specific data attributes is required. Columnar databases excel in handling large datasets and optimizing performance for analytics tasks like business intelligence and data warehousing. Examples include Amazon Redshift and Google BigQuery, which are widely used for data-driven decision-making processes and real-time analysis.