The [front matter](../markdown-features/markdown-features-intro.mdx#front-matter) is used to provide additional metadata for your doc page. Front matter is optional—Docusaurus will be able to infer all necessary metadata without the front matter. For example, the [doc tags](#doc-tags) feature introduced below requires using front matter. For all possible fields, see [the API documentation](../../api/plugins/plugin-content-docs.mdx#markdown-front-matter).
Optionally, you can add tags to your doc pages, which introduces another dimension of categorization in addition to the [docs sidebar](./sidebar/index.mdx). Tags are passed in the front matter as a list of labels:
How the Markdown files are arranged under the `docs` folder can have multiple impacts on Docusaurus content generation. However, most of them can be decoupled from the file structure.
### Document ID {#document-id}
Every document has a unique `id`. By default, a document `id` is the name of the document (without the extension) relative to the root docs directory.
For example, the ID of `greeting.md` is `greeting`, and the ID of `guide/hello.md` is `guide/hello`.
```bash
website # Root directory of your site
└── docs
├── greeting.md
└── guide
└── hello.md
```
However, the **last part** of the `id` can be defined by the user in the front matter. For example, if `guide/hello.md`'s content is defined as below, its final `id` is `guide/part1`.
```md
---
id: part1
---
Lorem ipsum
```
The ID is used to refer to a document when hand-writing sidebars, or when using docs-related layout components or hooks.
### Doc URLs {#doc-urls}
By default, a document's URL location is its file path relative to the `docs` folder. Use the `slug` front matter to change a document's URL.
For example, suppose your site structure looks like this:
```bash
website # Root directory of your site
└── docs
└── guide
└── hello.md
```
By default `hello.md` will be available at `/docs/guide/hello`. You can change its URL location to `/docs/bonjour`:
`slug` will be appended to the doc plugin's `routeBasePath`, which is `/docs` by default. See [Docs-only mode](docs-introduction.mdx#docs-only-mode) for how to remove the `/docs` part from the URL.
Our recommendation for file system organization is: make your file system mirror the sidebar structure (so you don't need to handwrite your `sidebars.js` file), and use the `slug` front matter to customize URLs of each document.
