SDLC Phases: Requirements, Design, Implementation
What you'll learn: How the first three core phases of the SDLC transform an idea into working software through structured steps.
The Three Foundation Phases
Think of building software like constructing a house. You don't just start hammering nails randomly—you follow a deliberate process. The SDLC's first three phases establish this foundation.
Requirements: What Should We Build?
This is where stakeholders (clients, users, business owners) define what they need. Engineers gather these needs through interviews, documents, and discussions. The goal: create a clear list of what the software must do.
Example: "The app must let users log in with email, search for products, and save items to a wishlist."
Without clear requirements, you might build something nobody wants—wasting time and money.
Design: How Will We Build It?
Now architects and senior engineers plan the structure. They decide how components connect, what technologies to use, and how data flows. This is the blueprint phase.
Example: "We'll use a web server to handle requests, a database to store user accounts, and separate the search function into its own module."
Good design makes implementation smoother and future changes easier (remember: engineering for change).
Implementation: Building the Actual Code
Finally, developers write the code based on the design. They translate plans into working software, one feature at a time. This is where programming skills directly apply.
Example: Writing the actual login function, database queries, and user interface elements.
Why This Order Matters
Each phase builds on the previous one. Skipping requirements leads to building the wrong thing. Skipping design leads to messy, hard-to-maintain code. These phases reduce uncertainty and risk—key engineering concerns you've learned about.
Key Takeaway: Requirements define what to build, Design plans how to build it, and Implementation creates the actual working software—each phase managing complexity and reducing risk.