Refactoring is the design phase in an agile process.
The old way, inspired by bridge building, I guess, was to first thing out a great design for your software, and then implement it.
This turns out to not work because, unlike bridges, software is always changing and needs new features.
So in agile, you just write the simplest thing that can possibly work to solve your next task. Then, when things work, you refactor the code to have a good design.
Designing something after it's built is a mind bending concept, but it's made possible by what we make being just text in files, not set in stone.
The old way, inspired by bridge building, I guess, was to first thing out a great design for your software, and then implement it.
This turns out to not work because, unlike bridges, software is always changing and needs new features.
So in agile, you just write the simplest thing that can possibly work to solve your next task. Then, when things work, you refactor the code to have a good design.
Designing something after it's built is a mind bending concept, but it's made possible by what we make being just text in files, not set in stone.