Data bases are stores of data that are: persistent (it is held held on some form of per enact medium), related (the data in a database isn't just a haphazard collection of facts), organised (the data is stored in a structured predictable way).
Many databases could be storing your information on the, right now. These include Spotify, iTunes, eBay and Amazon.
Different views of a database include the external view (what a customer might see of the database), the internal view (what someone building the database or editing it would see), and the physical view (the code that actually makes up the database).
Credits:
Created with images by Sean MacEntee - "database"