Understanding Pacific's sections
Sections is a Shopify feature that effectively allows merchants to assemble pages from customizable components (or sections!). This means tons of flexibility, especially on the homepage, where you can add, remove and reorder sections with just a few clicks. Examples of sections include featured products, slideshows, collection listings, or videos. You’ll access the customization options for all of them from the Sections tab in the theme editor.
The content on your homepage is made up of dynamic sections, meaning you can add and arrange as many as you want. A few notable exceptions in Pacific are the Header and Footer, as well as Promotions, which are fixed to various points on the homepage and cannot be repositioned—these are called fixed sections. (You can, however, still customize their content.)
Some other page types also make use of fixed sections. To see if the page you’re building has sections, open the theme editor and navigate to the page you’re working on within it. (For example, if you click through to your product catalog in the theme editor, you’ll see that a section pops up for Collection pages, giving you access to settings specific to that section.)