Lets you select objects and groups by clicking or dragging over them. You can also select groups within groups and objects within groups.
Direct Selection tool
Lets you select individual anchor points or path segments by clicking on them, or select an entire path or group by selecting any other spot on the item. You can also select one or more objects in a group of objects.note: When in outline mode, the Direct Selection tool may select imported graphics that are near the tool’s pointer. To avoid selecting unwanted graphics, lock or hide the graphics before making the selection.
Select objects with the Selection tool:
Tip: When the Selection tool is over an unselected object or group, it changes to. When it is over a selected object or group, the tool changes to . When it is over an anchor point on an unselected object, a hollow square appears next to the arrow
Excerpted from Adobe Help Site.