Two-Tier Architecture Explained Simply

In a two-tier model the client tier handles presentation (your PHP HTML pages) and the server tier handles logic and data — even without a traditional database.

When to Use It

Two-tier is ideal for small-to-medium applications where a full three-tier stack (client / application server / database) would add unnecessary complexity.

Flat-File as Data Tier

This very site uses PHP arrays as the data tier. In production you might swap them for JSON files, CSV datasets, or an external API — all without changing your presentation layer.

Scaling Considerations

When you outgrow two-tier, adding a database layer is straightforward because your business logic is already isolated in helper functions rather than mixed into your HTML.