The Loop is an extremely important topic in WordPress development: it is how WordPress renders a bundle of posts fetched from the database into an HTML webpage.
The Loop is a PHP while-loop that runs once per fetched post. Inside it, theme developers set repeated rules for how each post should display, primarily using WordPress's template tags.
The Loop should exist in every theme file that is part of the WordPress template hierarchy. Customizing The Loop is a major way in which themes create different views and layouts for webpages that display different kinds of posts (for example, Posts and Pages).
The Loop is perhaps the key concept of WordPress theming, so you'll definitely want to wrap your head around it. Fortunately, it's not that complicated! Our goal here is to make the concept clear first, and then to move on and show you how the code works.
The Loop in Plain English
In this section, no programming. We'll just go over basic concepts.