Please note that this is the Narutopedia's article on the original technique granted by the Rinnegan. If you are looking for the article on the technique which uses different bodies then you should head to Six Paths of Pain.
The Six Paths Technique (六道の術, Rikudō no Jutsu) is the origin of the unique techniques bestowed by the Rinnegan. In total there are actually seven of these paths that grant the user powerful and near god-like abilities:
The Deva Path (天道, Tendō), which allows one to manipulate both attractive and repulsive forces.
The Asura Path (修羅道, Shuradō), which grants the user mechanised limbs, weaponry and armour.
The Human Path (人間道, Ningendō), which gives the ability to remove a soul and so, read a person's mind.
The Animal Path (畜生道, Chikushōdō), which lets the user summon a wide variety of creatures.
The Preta Path (餓鬼道, Gakidō), which can absorb all forms of chakra, including most ninjutsu.
The Outer Path (外道, Gedō), which rules over both life and death.
These were all originally abilities that were used by one person, but because Nagato was crippled early on in his lifetime, he would go on to create the Six Paths of Pain. Through the use of the Outer Path, he was able to control six corpses as additional bodies and channel one of the first six of the aforementioned abilities into each, thus compensating for his physical limitations. However, while the strength and speed of the techniques are greater when used through the main body than when used through the corpses, and multiple Paths can also be activated simultaneously by the main body, there are advantages granted by the use of corpses. As the main body's vision is linked to the Rinnegan possessed by the corpses, the user is able to easily coordinate their movements and is given a form of protection, since the user can control the corpses from a distance, rather than putting their own body at risk.
Based upon the six Buddhist Paths of Reincarnation, each technique was named after one of the different "Paths": Deva, Asura, Human, Animal, Preta, and Naraka. Each of these Paths, or realms, represents one of the realms a being is reborn into after death, determined by the accumulated karma of their past lives. While the two lower Paths, Preta and Naraka, are hellish, and the two higher Paths, Deva and Asura, are heavenly, all six are considered to be Paths of suffering because they perpetuate the cycle of Reincarnation; the only way to break it and ascend to a higher state of existence is to attain enlightenment.
In Naruto Shippūden: Shinobi Rumble, a technique called "Six Paths Technique" is used by Nagato's Six Paths of Pain. In this variant, Nagato generates a moderately sized sphere of debris overhead, then thrusts his arms downward, sending it crashing into the ground like a meteor. An enhanced, "Full Throttle" version of the technique called "Six Paths Technique: Collapse" (六道の術・崩壊, Rikudō no Jutsu: Hōkai) can also be performed.
According to Kakashi and Guy, they have both developed countermeasures for each of those technique's but what they are is currently unknown.