A database is a structured set of data held in a computer, most often a server. Databases use a database management system (DBMS) that interacts with users, similar to a lookup table. Modern databases are designed to allow for the creation, querying, updating, and administration of the data it holds. There are different types of databases, including Relational Database Management Systems (RDBMS) that organize data into tables with predefined relationships, and NoSQL databases that provide a more flexible, schema-less approach to data storage.