Wado-Ryu Karate is a karate style.
The name Wado-Ryu has three parts: Wa, dō, and ryū. Wa means "harmony," dō (same character as tao) means "way," and ryū means "school" or "style". Harmony should not be interpreted as pacifism; it is simply the acknowledgment that yielding is sometimes more effective than brute strength.
To the untrained observer, Wado-Ryu might look similar to other styles of karate, such as Shoto-Kan. Most of the underlying principles, however, were derived from Shindō Yōshin-ryū an atemi waza focused style of Jujutsu. A block in Wadō may look much like a block in Shōtōkan, but they are executed from different perspectives.
A key principle in Wado-Ryu is that of tai sabaki (often incorrectly referred to as 'evasion'). The Japanese term can be translated as "body-management," and refers to body manipulation so as to move the defender as well as the attacker out of harm's way. The way to achieve this is to 'move along' rather than to 'move against'— or harmony rather than physical strength. Modern karate competition tends to transform Wadō-ryū away from its roots towards a new generic karate that appeals more to the demands of both spectators and competitors.
As with other styles of karate Wado-Ryu techniques move from the heels of the feet, but differ in that many (particularly the gyaku zuki reverse punch, like a boxer's cross) progress to incorporate pushing off the ball of the foot as well. This affects the delivery of a number of techniques, particularly adding reach to punches with the back hand, given the extra hip movement afforded utilising the balls of the feet in this fashion.
While the core principles (at least with regard to transmission of body weight into punches) of turning on the heel remain in Wado, as it is the fastest way to push the hips in the direction of attack, the progression to the ball of the foot is a hallmark of the style. It is important to remember that this in no way makes it superior or inferior as a system in comparison to other styles, it is simply another way of thinking that has both merit and drawbacks.
It works well with the jūjutsu applications that Wado retains and improves the tai sabaki that is a core of Wado training and application in comparison to the "low stances and long attacks, linear chained techniques" that typify the way Shoto-Kan developed after the split.