Extreme Wind Damage: Wind damage, area of shingles have come loose and slipped down. These have slid down together because the nails have come loose, but they are still attached to each other. These are pretty extreme, usually its more subtle.
Subtle Wind Damage: The chalk line illustrates the crease created - across and above the chalk line is wind damage.
The shingles ar not sealed down and flap in the wind, which puts a crease along the top of the shingle.
Hail Damage and Leaking Worn Shingles Damage:
Hail damage, on a fairly new roof, the hail knocks granules off the shingle exposing under lying mat to sun and weather damage. If left unattended they can turn into real problems.
Worn, older shingles are cracked and have noticeable granule loss, sometimes allowing leakage.