Align, distribute, and snap

Align

With two or more items selected, Object → Alignment offers six alignment actions: Align Left, Align Center Horizontal, Align Right, Align Top, Align Center Vertical, and Align Bottom. Each lines every selected item up against the edge (or center line) of the overall selection.

Distribute

Still inside Object → Alignment, with three or more items selected, Distribute Horizontal Spacing and Distribute Vertical Spacing even out the gaps between items along that axis, without changing the position of the outermost two.

Snapping

While dragging a single item, its edges and center automatically snap to the edges and center of nearby items once they're close enough — useful for lining photos up by eye without reaching for the Align menu every time.

Hold Alt while dragging to temporarily disable snapping for that drag, regardless of how close you get to another item's edge.

Snapping only applies to a single, unrotated item being dragged on its own — a multi-selection or an already-rotated item moves freely, since there's no single well-defined edge to snap in those cases.