For an explanation of the bundles concept see: Page bundles | Hugo
In short Page Bundles are a way to organize content.
For example for a project with the following structure:
.
├── config.toml
└── content
├── about.md
└── portfolio
│ └── index.md
└── posts
│ └── post-1.md
└── photos
└── _index.md
└── photo-1.md
.Site.RegularPages would list the generated pages of the following content files:
about.md
portfolio/index.md
photo-1.md
post-1.md
Regular stands for non-list pages or plain (leaf pages).
To create a leaf page bundle one needs to use a mandatory index.md .
For entering meta data on a section list (branch bundle) one needs to use an optional _index.md.
To limit the pages rendered by the .Site.RegularPages variable one can use the filtering techniques that are mentioned over here in the Docs.
