The Big Picture Constraints
Before writing a single line of code, you need a plan. Just as a structural engineer needs blueprints before pouring concrete, software engineers need an architecture before building complex systems.
Software architecture refers to the high-level structure of a software system — the decisions about how major components are organized, how they communicate, and how responsibilities are divided. These are the decisions that are expensive to reverse. Choosing the wrong database model, the wrong communication pattern, or the wrong deployment unit early on can cost months of rework later.
Architecture answers questions like: Can we deploy one part of the system without touching the rest? What happens when the payment service goes down — does the whole site go down too? Can ten teams work on this codebase simultaneously without stepping on each other?
There is no single "best" architecture. Every choice is a trade-off between simplicity, scalability, team autonomy, and operational complexity. This lesson walks through the main architectural styles used in production systems today, moving from tightly coupled designs to highly distributed ones, so you can reason clearly about which fits a given context.