Snapping to Head and Tail
You can drag and drop files to tracks and have them snap to the head or the tail of the current Edit selection or insertion point. When snapping to head, the beginning of the imported file snaps to the beginning of the Edit selection. When snapping to tail, the end of the imported file snaps to the beginning of the Edit selection.
To import and snap to head:

Control-drag (Mac) or Start-drag (Windows) a file onto a track.
To snap to head and copy the file to the project:

Option-Control-drag (Mac) or Alt-Start-drag (Windows) a file onto a track.
To snap to tail:

Command-Control-drag (Mac) or Control-Start-drag (Windows) a file onto a track.
To snap to tail and copy the file to the project:

Command-Option-Control-drag (Mac) or Control-Alt-Start-drag (Windows) a file onto a track.