  Context: Agile development methodologies in the software industry have
increased significantly over the past decade. Although one of the main aspects
of agile software development (ASD) is less documentation, there have always
been conflicting opinions about what to document in ASD. Objective: This study
aims to systematically identify what to document in ASD, which documentation
tools and methods are in use, and how those tools can overcome documentation
challenges. Method: We performed a systematic literature review of the studies
published between 2010 and June 2021 that discusses agile documentation. Then,
we systematically selected a pool of 74 studies using particular inclusion and
exclusion criteria. After that, we conducted a quantitative and qualitative
analysis using the data extracted from these studies. Results: We found nine
primary vital factors to add to agile documentation from our pool of studies.
Our analysis shows that agile practitioners have primarily developed their
documentation tools and methods focusing on these factors. The results suggest
that the tools and techniques in agile documentation are not in sync, and they
separately solve different challenges. Conclusions: Based on our results and
discussion, researchers and practitioners will better understand how current
agile documentation tools and practices perform. In addition, investigation of
the synchronization of these tools will be helpful in future research and
development.
