What this is and where it shows up
Every app you build has a database underneath it. It might be a tidy spreadsheet-style grid, a set of linked tables, or something more exotic — but it's there, and it's holding everything together.
The database is where your users live, your orders are stored, your content sits waiting to be displayed. When it works well, you never think about it. When it doesn't, you feel it everywhere: fields that don't quite fit, data that contradicts itself, a simple change that somehow breaks three other things.
Database design is the discipline of deciding what to store, how to organise it, and how to link it together before you start building. Database management is everything that happens afterwards — adding fields, changing structures, keeping data clean, and making sure the whole thing doesn't collapse when requirements change (and they always change).
If you're building with AI, this matters more than most people realise. AI tools will happily generate a schema for you in seconds. The question is whether that schema is built to last.