Well what I know about Taijutsu is that it is used for close hand to hand combat. It's is the incorporations of Martial Arts. I think there are a few ways in which you can use Taijutsu, one is using chakra, manipulating it to enhance your attackes etc, then you have people who lack the ability to mold chakra alone, making them capable of only using physical abilities like Lee. Though both are different, they both contain techniques that can shatter stones or provide impressive speed enhancements.
Three characters stick out to me when I hear or read the word "Taijutsu". Those the are Rock Lee, Might Guy and Kimimaro. All have exceptional skills if not the best in the Narutoverse.
Even though they use taijutsu in manners that defy the laws of science and physics, there is some realism in it. Besides the outrageous boosts of energy and supernatural sources of power, taijutsu all boils down to the basic movements. Consisting of momentum, force, velocity, flow and several others. Merging these very basic elements into one gives the user the ability to perform basic movement skills. Furthering in on this or going a little more in depth, the user is able to increase the strength and speed by applying a larger amount of these key elements. With chakra added into the mix, or more honed training skills, you can achieve a form or state of being that can perform these movements with utter ease.
Taking into consideration that this isn't your everyday, run of the mill life, certain things involved or used in combination with these key things provide a power beyond imagine. (Speaking RP wise of course)
Also, while training in taijutsu the user is able to improve strength, speed, and stamina. These are major factors in taijutsu and can give better results. For example if you take an average person who has just done martial arts training once a week for a few hours (in the narutoverse) and pit them against someone who has shed tears, sweat and blood to achieve the maximum potential their body is ultimately capable of, then the victor will be obvious. Due to the over stimulation and use of your muscular system, taijutsu techniques can be dangerous on the body, putting it under constant pressure and causing recoil damage. With enough training these type of things can be dulled down or removed completely giving you the optimum results in battle.
Understanding taijutsu and learning about taijutsu are one in the same. Having no knowledge of how to use the power accurately will show results dwindling on the brink of weakness. By completely understanding your own body and the flow in which your body moves at, the user is able to achieve much more power, speed and stamina in turn.
I think I covered the basics. Of well, what I know in my own head, or what I think it is >_>