Scarification means scratching or cracking the hard outer coat of a seed to help it germinate.
Some seeds, like Morning Glories and Lotus, have outer shells that are extremely hard and don’t allow water through. This is one way a seed stays dormant in the fall and winter, until growing conditions improve.
Animals can also scarify seed by eating the hard seeds and digesting them. This is how strawberries can make their way around your yard.
Gardeners can scarify seed by gently rubbing the seed with something coarse, like sandpaper or a file, or by making nicks in the shell with a knife. You have to be careful when doing this. You only want to crack the shell, not damage the seed inside or your fingers.
Another way hard seeds can be cracked open is by leaving them outdoors throughout a cold winter. The constant freezing and thawing will be enough to get the to eventually crack. This process is generally referred to as stratification or cold stratification. Some seeds are not hardy enough for cold winter temperatures, but many perennial plants are started this way.