In the webtoon "Solo Leveling," solo dungeons play a crucial role in the leveling up of the protagonist, Sung Jin-Woo. These dungeons are personalized instances tailored to the user's strength and abilities. By successfully clearing these solo dungeons, Jin-Woo gains experience points, levels up, and acquires new skills and abilities. Solo dungeons serve as a training ground for Jin-Woo to become stronger, hone his combat skills, and prepare for more significant challenges he will face in the future.