The Loop is PHP code used by WordPress to display posts. Using The Loop, WordPress processes each post to be displayed on the current page, and formats it according to how it matches specified criteria within The Loop tags. Any HTML or PHP code in the Loop will be processed on each post.
WordPress Codex: The Loop
The loop will start with code that checks to see if the current page is supposed to display a listing of several posts or just one post. If a page is supposed to list blog posts, then it will list out a title and excerpt for each post. If the page contains only a single page or a single post, then the loop will display the content for that page. Continue reading WordPress Words: The Loop