Smart Guides (View > Grids & Guides > Smart Guides) are temporary snap-to guides for alignment.
Grouping content:
Select the Selection tool in the Tools panel. Drag across content or Shift-click to select it. Click the Group button in the Properties panel to group the objects.
With the Selection tool, double-click an object in a group to edit it individually. Press Escape to stop editing and regroup the objects.
Aligning content:
To align objects to one another, select the objects to align, then select an align option in the Properties panel or in the Align panel (Window > Object & Layout > Align).
Choose an option from the Align To menu in the Properties panel to align content to the page, margins, or other elements on the page.