> For the complete documentation index, see [llms.txt](https://community.commandersact.com/web-container/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://community.commandersact.com/web-container/user-manual/data-layer-and-data-types-1.md).

# Data layer and data types

The data layer represents all your available data. It consists of **information about your site** (e.g. page name, product ID) **and your visitors** (e.g. user ID, customer status) in the form of **JavaScript variables**.

![](/files/-LnwHnkG24LUsJSq1bef)

These variables have two uses:

– To populate the tags present in your container;

– To create activation rules for your tags.

Additional information:

The data layer can consist of two types of data:

– Data implemented by your IT department or your technical provider for all your web pages, based on the CSS, Backoffice and CRM. These data are called “**external variables**” and are displayed in your site’s source code as a **JavaScript object** containing all the variables used by your tags.

This is what the external variables look like in the source code:

![](/files/-LnwHwRte906k9ppIAyZ)

– Data created in the interface by **Commanders Act staff** or **TagCommander** users based on information available on the site’s pages (URL, cookies, HTML tags, external variables in the data layer, etc). They are called “**internal variables**” and are displayed in the **TagCommander container’s code**.