When would one use an executive summary?

Every time you present your results to a person in a managerial position or who does not have expertise in the technical details and processes you followed to get your results

Explanation:

When it comes to software projects documentation, you generally have to build a report that will be read by different people. These people come from different backgrounds and know the project to a different extent. For this reason, the project should contain sections that facilitate the understanding of the reader.

In general, the first section of a project report is an executive summary. The executive summary is a concise description of the project, starting from the problem context and description, including the results, conclusions, and recommendations.

It should be no more that one page long and it should be written in a general language so whoever reads it understands what is your project about.