#### This Page

# URLs and Slugs

Lektor's URLs in general mirror what happens on the file system as much as possible. There are however various cases in which this behavior can be changed.

## A URL Is Composed of Slugs

Each page in Lektor is associated with a string called a slug. The full URL of a page is its own slug concatenated with the slug of each its parents.

The default slug is the ID of the page. So the page `content/foo/bar/contents.lr` has the default slug `bar`, its parent has the default slug `foo`, and its default URL would be `/foo/bar/`.

## Slug Customization

Slugs can be customized. They can even contain slashes (see below). There are three systems that control what the slug looks like:

### Folder Name

The name of the folder that contains the `contents.lr` file is the ID of the page and thus the default slug (unless changed by the model — more about that later). This means that you could for instance just rename the folder to get a different slug. This is the recommended way for the majority of pages to adjust the slug.

### The `_slug` System Field

The second option is to use the `_slug` system field. This field is available for all models automatically and overrides the slug explicitly. This is particularly useful to force a slug that could not be represented on the file system (for instance because it should contain a slash) or because you want to change the slug for a different Alternative. As an example a page translated to German might want to translate the slug as well.

### Implied Slug Configuration

The last part is a system that controls the implied slugs. In particular it means that the model of the parent page can override the default slug for all of the children below it. This for instance can be used to automatically add the date of a blog post into the slug. For more information about this feature see Children & Pagination.

## Slugs Containing Slashes

Slugs can indeed contain slashes. It's perfectly valid for a page to have `2015/5/demo` as slug, and it will still be incorporated into URLs as described above. What's not possible is for a page to pretend that it belongs to a different parent. The parent paths are always added to it. So once a page has a parent page `/foo` its URL path will always begin with the URL path of the page `foo`.

## Extensions and File Types

The default behavior for a page is to build into a hidden `index.html` file. This means that if you have a page called `foo/bar/contents.lr` it will build into a file named `foo/bar/index.html`. Web servers typically look for an `index.html` file in a folder which is why you can just access `/foo/bar/` and the page will render.

If however the last path component contains a period (`.`) then the last path component is assumed to be a filename directly. This means that if you set the slug of a page to `404.html` for instance, the page will indeed render into `404.html` and not `404/index.html`.

However you need to be careful with this as web servers pick the “mimetype” of a file based on the extension. So if you name a file `foo.html` it will behave very differently compared to a file named `foo.txt`. So do not name your files in ways that would be incompatible with what the web server renders. This however also allows you to generate files that are not HTML. For instance you could render into a `.xml` file if that is what you want.

This feature is called “Dotted Slugs” and there are some specifics with regards to how these are handled.

## Content Below Dotted Slugs

One specific behavior of a path component that contains a dotted slug is that content below that path need to move to a different location. Imagine for instance you named the page `404.html` but that page has an attachment. As `404.html` is now a file it's impossible for a folder with the same name to exist. This means that the attachments have to be stored elsewhere. The convention for this in Lektor is to prefix the path with an underscore. So if `404.html` has an attachment named `foo.jpeg` it will move into `_404.html/foo.jpeg`.

## External and Absolute URLs

Lektor by default will prefer relative URLs. This makes it possible to easily host a website below a certain folder without having to do anything special to make this work. However there are some features which will require the use of an absolute or fully canonical (external) URL. For instance sitemaps or Atom feeds do not work with relative URLs. In this case the absolute URL path has to be configured.

You can pick the default for URL generation in the project configuration. For more information read about the Project Configuration.

The default of `relative`, a relative URL style, means that you can deploy a website to a sub folder without any configuration, however most likely custom 404 pages will fail to find the needed assets. Fully canonical URLs are not recommended as default style.

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