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The following is the video's transcript:
Long, beautiful nails give the appearance of culture and sophistication. Horizontal ridges in your nails are normally caused by trauma to the area just below the cuticle at the base of your fingernail. These can also be caused by some illnesses and medications.
Vertical ridges may be caused by genetic predisposition or by some sort of permanent injury to the area where the nail is formed. These are quite common, and can become more obvious as you age.
If your ridges are visible but not dramatic, then you can simply cover them. As you apply polish, it will fill in the ridges before drying. Deeper ridges may take several coats, but most of them can be covered with only a little effort.
More dramatic ridges may require some additional effort. You might try using a very fine emery board to remove the ridges, but be careful that you don't "grind down" the nail thickness too much. Doing so may replace a small problem (the ridges) with a bigger problem (too-thin nails). After using the emery board to smooth out the ridges, rinse the nail with clean water, dry it completely, and then apply nail polish as you normally would.
For a longer tip related to this subject, see Removing Fingernail Ridges