A relational database is different from flat files that you might create with a spreadsheet or a word processor.
Flat files are easy to set up, but difficult to maintain.
When you update these items, it is tedious to find all of the places they occur and type in the same information over and over. Afterward, you are never completely sure that all copies are the same. There is also a risk of deleting important data, then finding that there were no copies elsewhere. A properly designed relational database stores each item in only one table, pointing to that table from other tables of related information. Data can be pulled from sets of related tables as though they were all stored together.