Chakra Vortices (チャクラの渦, Kadou Chakra; Also named "Chakra Vortexes") are pools or waves of chakra found around the body of shinobi. Generally called "aura" by many, these vortices are different in the sense that they cannot be seen by the mortal eye. Chakra normally flows in a circular motion, and everyone's chakra movement follows a similar pattern to the way their hair is grown at birth. By seeing at what direction one's hair grows towards, the left or right, this can be used to determine how their chakra needs to flow in order to learn jutsu more easily. Only an eye that does "not belong" in this world can see these vortices; namely, the Rinnegan.
When a user of the Rinnegan is able to spot these pools of energy, they are able to attack these vorticies with a burst of chakra from their end, allowing them to disrupt the use of jutsu or completely disable a jutsu prior to it's activation. The more levels of chakra a being possesses, more chakra vortices will be present around them. Using the Blade of Bonds in unison with the spotting ability of the Rinnegan, allows it's wielder to access the Kikanyuha (ミラー波, Mirror Wave); which can use the power of the vortices to control a jutsu being launched but an opponent, and turn it back against them, usually doubling the attack power of when it was initially sent out.
Kisame's Samehada sword worked in a similar way, however Kisame did not search for the vortices; Samehada was a blade that did not naturally exist in the world, and this allowed for it to be able to track the chakra vortices and absorb them instead of destroying them, allowing it to gain their chakra.