The Sharingan's first and most well known ability is to memorize any technique that it witnesses. It can memorize Ninjutsu, Genjutsu, and Taijutsu with perfect accuracy, allowing the user to use the techniques as his own. In order to reproduce copied jutsu, however, one must have the necessary skill or ability to perform them. A prime example is Rock Lee's brand of Taijutsu. While Sasuke was able to copy some of Lee's moves, they put a much more significant strain on him since he hasn't trained physically nearly as hard as Lee has. In addition to physical skill, the Sharingan cannot allow the user to reproduce other Kekkei Genkai since the Sharingan user doesn't possess the same genetic trait. Additionally, Sharingan users cannot summon a creature which they have not made a contract with.
The Sharingan also grants the user incredible clarity of perception, allowing them to track fast-moving objects with ease and even predict the subsequent movements of those objects. The ability to track and predict movement is largely based on individual skill, as unskilled users have much more trouble tracking fast-moving objects. A fully-evolved Sharingan eye can track all but the quickest opponents, even if the user can't move at the same speed, (so even if the user can follow his or her opponents movements it doesn't necessarily mean their body will be able to react fast enough even though they saw the attack coming). This perception is also great enough to see through Genjutsu, depending upon the skill of the user, and the ability to observe the movement and flow of chakra, but not to the same extent or clarity as the Byakugan. Another ability of the Sharingan is the ability to see chakra as color, even through other objects. For example when Sasuke fights Deidara, he can see Deidara's bombs hidden under ground because of their chakra. Additionally, the Sharingan grants the user exceptional analytical powers, allowing them to instinctively pick up on various visual clues with little difficulty. In one instance, Kakashi had to shut his eyes to avoid accidentally reading Naruto's lip movements while he was spoiling the ending of one of Kakashi's Icha Icha books. Sasuke was also able to reproduce answers on another person's test by watching their pencil movements during the Chunin Exam.
The Sharingan also is capable of a unique brand of hypnosis that involves suggesting actions and thoughts to the opponent through simple eye contact. When used in conjunction with the other aspects of the Sharingan, this allows the user to perfectly mimic every move their opponent makes, even before they do, making it appear as if the user can see the future. More advanced Sharingan users can take the hypnosis ability even further by tricking or even trapping their opponent within an illusion. The potency of the Sharingan's illusion is dependent on the user's knowledge and skill with implementing Genjutsu.
The Sharingan also grants the user incredible clarity of perception, allowing them to track fast-moving objects with ease and even predict the subsequent movements of those objects. The ability to track and predict movement is largely based on individual skill, as unskilled users have much more trouble tracking fast-moving objects. A fully-evolved Sharingan eye can track all but the quickest opponents, even if the user can't move at the same speed, (so even if the user can follow his or her opponents movements it doesn't necessarily mean their body will be able to react fast enough even though they saw the attack coming). This perception is also great enough to see through Genjutsu, depending upon the skill of the user, and the ability to observe the movement and flow of chakra, but not to the same extent or clarity as the Byakugan. Another ability of the Sharingan is the ability to see chakra as color, even through other objects. For example when Sasuke fights Deidara, he can see Deidara's bombs hidden under ground because of their chakra. Additionally, the Sharingan grants the user exceptional analytical powers, allowing them to instinctively pick up on various visual clues with little difficulty. In one instance, Kakashi had to shut his eyes to avoid accidentally reading Naruto's lip movements while he was spoiling the ending of one of Kakashi's Icha Icha books. Sasuke was also able to reproduce answers on another person's test by watching their pencil movements during the Chunin Exam.
The Sharingan also is capable of a unique brand of hypnosis that involves suggesting actions and thoughts to the opponent through simple eye contact. When used in conjunction with the other aspects of the Sharingan, this allows the user to perfectly mimic every move their opponent makes, even before they do, making it appear as if the user can see the future. More advanced Sharingan users can take the hypnosis ability even further by tricking or even trapping their opponent within an illusion. The potency of the Sharingan's illusion is dependent on the user's knowledge and skill with implementing Genjutsu.