Theme structure
The overall layout of your online store is controlled by your theme. Your theme uses templates to specify how content appears in your store on specific pages or page types. A template is made up of sections, which are composed of blocks. Sections and blocks are modules that you can use to customize the layout of your online store.
Templates are customized by adding, removing, and rearranging sections and the blocks within. You can have up to 25 sections for each template, and each section can contain up to 50 blocks. Not all sections will have individual blocks to customize.
For example, if you make unique handcrafted items, then you might create a not-for-sale product template to apply to all products you've already sold. This template might have two sections: Product information and Related products. The Product information section might have only the Title and Description blocks, as you wouldn't want to display things like quantity selectors or buy buttons if a product isn't available to purchase.
Saved templates can be applied to new or existing pages and products using the theme editor or your Shopify admin. Sections can be customized and added to any page of your online store, with the exception of gift card and checkout pages.