Some elements can be containers (found in the container section of the New Element palette), and all elements in Bubble belong to a parent. The page itself is the top parent, and all elements on the page will have the page as their parent. To draw an element inside a container, move your mouse over the container, and you'll notice the borders turn red. Once an element is inside a container, its behavior will follow the parent's behavior, both in Edit and Run-mode. For instance, if you move an element in the editor, the children will stay at the same place relative to their parent. In Run-mode, if you hide a parent, any element inside the container will be hidden as well and, if you show a parent, any element inside it will become visible too. Dragging an element lets you change its parent.