These days, Zen could be divided up into three kinds of Zen. The first is dead word Zen or the same, literati Zen. This is Zen that believes the words of the Zen masters, as especially found in koans, are interpretable. This Zen assumes that the concept forming intellect is capable of cracking the koan's secret.
The second kind of Zen is live word Zen which is Zen that aims a kensho which means to see one's Buddha-nature, directly. We might even call this Zen, kensho Zen. With such Zen the words of the Zen masters are not interpretable. Their words and strange gestures are barriers—like the monkey pitch ball trap. Touch a koan with your intellect, you're caught in the pitch ball trap. The only way to escape the trap is to apply the huatou which literally means "ante-word" or "ante-thought". This means to turn the light of mind back to what, essentially, preexists mind-become-thoughts in which mind transcends birth and death. This is mind that is pure, unconditioned, and radiant.
The third kind of Zen is sitting Zen. This Zen is based on the physical practice of sustained sitting in a rigid upright posture. It is used mainly by those who follow the teachings of Dogen Zenji. Originally, this practice was developed by Zen master Hung-chih and known as Silent Illumination Zen which made its way to Japan through Dogen Zenji which then became the school of Soto Zen. Hung-chih taught, “Just being completely silent we are naturally illuminated.” This practice was highly criticized by other Zen masters. Zen master Hakuin Ekaku (1686–1769), who fixed the orthodox Rinzai koan practice, called it "dead sitting in silent illumination" (koza mokushô).