> For the complete documentation index, see [llms.txt](https://magdalenaolak.gitbook.io/istqb-foundation-level/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://magdalenaolak.gitbook.io/istqb-foundation-level/2-testing-throughout-the-software-development-lifecycle/2.1.-software-development-lifecycle-models.md).

# 2.1. Software Development Lifecycle Models

A software development lifecycle model describes the types of activity performed at each stage in a software development project, and how the activities relate to one another logically and chronologically. There are a number of different software development lifecycle models, each of which requires different approaches to testing.

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[2.1.1. Software Development and Software Testing](/istqb-foundation-level/2-testing-throughout-the-software-development-lifecycle/2.1.-software-development-lifecycle-models/2.1.1.-software-development-and-software-testing.md)
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[2.1.2. Software Development Lifecycle Models in Context](/istqb-foundation-level/2-testing-throughout-the-software-development-lifecycle/2.1.-software-development-lifecycle-models/2.1.2.-software-development-lifecycle-models-in-context.md)
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