Page Blocks are the web pages the end-user clicks through in your app. Your app must have at least one Page Block.
Each Page Block is presented to the end-user in the order in which you sequence them in the App Builder:
Page Blocks are the visible "front-end" of your app. Logic Blocks are the invisible "back-end." Simple apps may not have any Logic Blocks, but all apps must have at least one Page Block.
Because Logic Blocks are invisible, it does not matter how you sequence them in the App Builder.
You can toggle between viewing all blocks, only pages, and only logic:
By default, every Page Block will be displayed to the end-user in the order they are arranged. You can add conditional logic to a Page Block to display it only under certain conditions.
To add "display if..." logic to a Block, simply click the "display if..." toggle:
Clicking this toggle allows you to edit a logical expression. If that logical expression is true (or, as we say, if it "evaluates to true"), then and only then is the Page Block displayed to the end-user.
You can learn about editing logical expressions here.
There are many different types of Page Blocks, each with their own purpose:
You can collect a set of Page Blocks into a "loop." These Page Blocks will be presented to the end-user over and over, as long as the end-user opts to continue the loop. This is how we allow you to collect information about X number of things.
The classic example for a loop is collecting information about an end-user's children. In Afterpattern apps, you can't ask the end-user "how many children do you have?" and then use their response to determine how many times you ask for a child's name and social security number. Instead, you must use a Loop Section.
You can learn more about loops here.