Which Liquid tag is used to include snippets in Shopify themes?

The use of the 'render' tag in Liquid to include snippets in Shopify themes is correct because it is specifically designed for this purpose. When you call a snippet using the 'render' tag, it allows you to bring in the functionality or markup defined in that snippet file. This method efficiently handles isolation, optimizing the rendering process by not passing variables between the current template and the snippet.

Furthermore, using 'render' promotes better performance since it creates a new scope, meaning that any variables defined in the template calling the snippet won't interfere or mix with the variables inside the snippet. This separation helps avoid potential variable name conflicts and enhances the modularity of your theme components.

Alternative methods of including content, such as using an 'include' tag, were used in prior versions of Liquid but have been deprecated in favor of 'render' due to its improved performance and scope management. The other options in the question, such as 'source' and 'snippet', do not represent actual Liquid tags used for snippet inclusion within a Shopify theme. The 'render' tag is the preferred and current practice for including snippets, ensuring best practices in theme development.