Fixing cracks in drywall (also referred to as wallboard, gypsum board, or Sheetrock) is essential because drywall damages easily. Repairing small cracks in drywall is also easy. The best way to fix a small drywall crack is with flexible silicone caulk.
Hairline cracks in drywall are caused by movement in the foundation or framing of the house. The frame of your house expands and contracts with the seasons. The silicone will flex as the crack widens and narrows with normal house movement.
Buy a fresh tube of paintable silicone caulking.
Caulking is useless once it becomes dry.
Apply a thin bead of caulk into the crack.
Be sure to get the caulk actually inside the crack.
Smooth out the caulk bead.
You can use a wet finger if the crack is small enough. If not, use a 5-in-1 tool or a putty knife.
Clean away excess caulk.
Wipe the excess caulk away from the outside of the crack. Rubbing alcohol works great.
Paint over the patch with primer.
Don’t skip this step or you’ll end up with a permanently goofy-looking, non-matching area.
Apply touch up paint to the patch in your wall color.
This is why you saved that half a gallon of leftover wall paint.