How do I sharpen a kitchen knife at home?

The easiest home method is to use a whetstone. Soak it in water for about 10 minutes, then hold the knife at a 15 to 20 degree angle against the stone and push the blade forward while sliding it across, as if you're trying to shave a thin layer off the stone. Repeat on both sides, alternating strokes until you feel a slight burr on the opposite edge, then finish with lighter strokes to remove it. If you don't have a whetstone, a honing steel realigns the edge and should be used regularly between sharpenings. You can also use the unglazed ceramic bottom of a coffee mug in a pinch, dragging the blade at the same angle a few times per side.