What Is the SDLC? Software Development Life Cycle, Explained

The SDLC (software development life cycle) is the process software moves through from first idea to switch-off: planning, design, development, testing, deployment, and maintenance. It maps how software gets built and kept alive.

Teams walk that map differently. Waterfall runs the phases once, in order, and suits work where the requirements genuinely cannot move. Agile cycles through them in short iterations: ship something usable early, then refine it. Most teams land somewhere between the two.

The phases matter more than the methodology label. Planning decides what to build and why. Design settles the architecture and the interfaces. Development writes the code. Testing proves it works, deployment puts it in users' hands, and maintenance keeps it useful while the business changes around it. Skip a phase and it collects interest. Software shipped without real testing gets tested by its customers.

A six-week dispatch tool for a freight forwarder still runs all six phases: a week of discovery, a clickable prototype, two build rounds with dispatcher feedback in between, then launch and a maintenance rhythm.

Why it matters for custom software

AI-assisted development compresses the SDLC. It doesn't delete it. Writing code is the part that got dramatically faster, so the weight of the work shifts to everything around it: sharp requirements, honest testing, maintenance someone actually does. That is what how we work is built around, and why a fixed six-week delivery is possible at all.