Databases are integral to modern computing, providing a means to store and organize data for easy access and analysis. The history of databases began with early computing, evolving significantly in the 1960s and 1970s with the development of relational database management systems and SQL, which enabled data to be stored in tables. As the internet expanded in the 2000s, the demand for handling vast amounts of data led to the development of NoSQL databases and big-data processing technologies. More recent advancements include streaming databases optimized for real-time analysis and application-specific databases for niche use cases. Databases can be categorized into analytical versus transactional, relational versus non-relational, distributed versus single-node, and in-memory versus on-disk, each serving distinct functions and optimized for different use cases. SQL, a declarative programming language, is commonly used to interact with databases, though its implementation varies among systems, with some databases like Redis not using SQL at all. The series promises to explore these topics further, delving into the complexities and functionalities of different database systems.