Most web applications require databases for storing data. If the data is normalised (Where one table is related to another through an Identifier) then most likely a Database Management System like Mysql, PostgresSQL or SQLite would be used. Access to data using these is by SQL.
One of the things that need to be seriously considered when managing a data is backing up your database.
My friend and Colleague in the Laravel UK Slack channel, Simon Bennet wrote a great article on The Ultimate Guide to mysqldump. It is very good learning resource for novices and good reference for those who are experienced. Visit the link here https://snapshooter.io/learn/mysqldump-ultimate-guide