Use an app block when the feature belongs in one spot on the page. Use an app embed for things that float, overlay, or run without showing. Blocks are easier to place and remove.
App blocks let you add, remove, and move app features in the theme editor exactly where you want them. App embeds float, show as an overlay, or add code without being visible to customers.
If you can point to where the feature should sit, it is a block. Reviews under the price, a size chart by the variant picker. Chat bubbles and tracking are embeds. Turn off embeds you cannot name a job for.
Source: Shopify Help Center, Extend your theme with apps. Reviewed Sep 23, 2026.
A template decides which page type you are editing, like product or collection. Sections are the movable content blocks inside a template, such as a gallery, a featured collection, or a text row. Modern Shopify themes let merchants rearrange sections on most templates without touching code.
Always work on an unpublished copy for anything beyond a tiny text change. Preview the copy, test the cart and checkout paths, then publish when it checks out. Keeping the previous version as your rollback copy turns a bad publish into a two minute fix instead of a scramble.