From Shopify Wiki
Following is a reference-list of objects which you can use in your liquid templates. For a introduction to liquid templates you can check out the UsingLiquid page.
The following variables must be included in your theme's layout file (theme.liquid).
- [[Content_for_header|Template:Content for header]]
- [[Content_for_layout|Template:Content for layout]]
Template specific objects
Special purpose templates usually export the object they reference by the same name as the template file. Product.liquid, for example, would export a product object which references the current product on the page.
All current email templates shown in your Email & Notifications Preferences screen have access to the properties of their respective order.
Shipping notification templates
The following objects are available from any liquid template in your shop's theme.
In addition, current_tags is available in both collection.liquid and blog.liquid.