If you work with a database-driven script application for your site, all content that you or the site users add, will be kept in cells and tables within a database, not as plain text in the app files. In comparison, HTML sites are static and all of the content on such a site is a part of the actual HTML files. An online store application, for instance, pulls all the prices, items, user reviews, and many others, from its database and this is valid for any other script that allows you to make a dynamic website. The more the info you insert, the larger the database will get, so if you use a script-driven site, you should make sure that your hosting package comes with adequate database storage space. The aforementioned applies no matter what kind of databases you will use - for example MySQL or PostgreSQL.