This document provides an overview of different types of databases and how to choose the right one. It discusses relational databases like MySQL and SQL Server which use tables and relationships. NoSQL databases like Cassandra and MongoDB are discussed as being schema-less and storing data together. Evented databases like Kafka are covered as focusing on transient data through events and producers/consumers. Key factors in choosing a database are also outlined like scalability, querying capabilities, use cases and storage structure.