What are the environments a software product can go through. Up to now I've only seen:
Anything else?
You are right. The tradicional way of software development (called waterfall) following these steps. Althrough in past then years many methodologies are created and them are improve the software development process nowadays.
If you don't now about the methodologies like Extreme Programing (XP), Test Driven Development (TDD), Scrum, Kanban , Behaviour Driven Development (BDD), Agile Unified Process, Feature Driven Development (FDD) and others Agile Methodologies (very common in these days) don't worry about. There are many material in the Internet. Some of that these methodologies are focused in the building and test software in the source code level (TDD, BDD), others are more focused with the management of the entire process (Scrum, Kanban).
Bu the manly idea in the subset of these methodologies is that the requirements change during the process and that is necessary to complement the stage of development with the test stage in small interactions to delivery a piece of software with valuable functionality in little cycle instead to follow inflexible traditional way to produce software that doesn't matter.