A database is software that manages data inclduing storing, indexing and performing queries. Some are internal to an application, but many run as a service used by multiple applications, either running on a central computer or using some form of cloud service. The most common forms are relational databases (effectively collections of large, interconnected tables) and noSQL databases, which use simple key-value bindings to JSON objects.
Used in Chap. 2: pages 16, 17, 18; Chap. 3: pages 25, 32, 33; Chap. 5: page 71; Chap. 10: page 132; Chap. 12: page 180; Chap. 13: pages 189, 193, 198, 200; Chap. 14: page 218; Chap. 16: page 238; Chap. 17: pages 251, 253, 254; Chap. 21: page 332; Chap. 22: page 344