Wing Chun, occasionally romanized as Ving Tsun or "Wing Tsun" (literally "spring chant" and alternatively as "forever spring", or substituted with the character for "eternal springtime") is a Chinese martial art that specializes in aggressive close-range combat.
The characters (永春) "forever spring" are also associated with some other southern Chinese martial arts, including Jee Shim Weng Chun (Yong Chun) and White Crane Weng Chun (Yong Chun).

History
The history of most martial arts, including Wing Chun, has historically been passed from teacher to student as an oral history rather than through written documentation, making it difficult to confirm or clarify the differing accounts of Wing Chun's creation. Some have sought to apply the methods of higher criticism to the oral histories of Wing Chun and other Chinese martial arts. Others have attempted to discern the origins of Wing Chun by determining the specific purpose of its techniques. Wing Chun starts to appear in independent third-party documentation during the era of the Wing Chun master Leung Jan, making the subsequent history of Wing Chun and its divergence into branches more amenable to documentary verification.
The common legend involves Yim Wing Chun (Wing Chun literally means beautiful springtime or everlasting spring). A young woman who has rebuffed the local warlord's marriage offer, and he says he'll rescind his proposal if she can beat him in a fight. She asks a local buddhist nun, Ng Mui, to teach her boxing, and the style they develop enables Yim Wing Chun to defeat the warlord and she marries her sweetheart and teaches him the style which he names after her.
It should be noted that the system was developed during the Shaolin and Ming resistance movement against the Qing Dynasty and thus many legends about the creator of Wing Chun were spread to confuse the enemy, including the story of Yim Wing Chun, this may have contributed to why no one has been able to accurately determine the creator or creators of Wing Chun.

Practicality
Wing Chun techniques emphasize practicality and efficiency to maintain its ideals on effectiveness. Strikes are intended to injure or disrupt the target. Efficiency in Wing Chun is based on the concept that the shortest distance between two points is a straight line. Likewise its primary targets all lie along the "centerline" of one's opponent.

Efficiency
Wing Chun believes in using the least amount of required force in any fighting situation. It believes properly timed positioning and movements can and should be used to defeat an opponent. This is achieved through balance, body structure and relaxation. The Chinese saying "4 taels to move 1000 catties" (referring to an old Chinese measurement system) is appropriate here in describing how a small amount of force, correctly applied, can deflect a powerful attack.
Wing Chun uses deflection and counter-attack in the same motion or will intercept the opponent to nulify an attack, rather than blocking then attacking in two separate motions. Further on interception the punch can act as a block as a consequence of the structure and the position of the arm travelling along its triangular "power-line" pathway to the opponent's "Core". This means that the opponent's attack is automatically deflected by the arm-structure of the Wing Chun practitioner as the counter-punch is delivered.
The "structure" permits this deflection to occur is controlled through the correct focus of energy from the "core" to the "elbow". If the structure is not in place, the counter-attack/interception is likely to break down losing the "forwarding" power which may result in the deflection failing and allowing the attacking punch to make its target.
In addition to efficiency being understood as the "shortest distance to the opponent's core" (which relates specifically to the speed of attack/counter-attack), it is also important to understand the importance of energy efficiency within Wing Chun. A person using Wing Chun is said to be able to defeat a stronger person because they are able to use their structure effectively. Given this, it is essential in ensuring that the Wing Chun practitioner has a full understanding of structure which enables them to use the correct use of energy required - any deviation from their "structure" resulting in using muscles in the shoulders will cause injury to the practitioner and also result in fatigue very quickly. This deviation removes the Wing Chun practitioners advantage since their "structure" will no longer support the defence/attack and vice versa. So the conclusion of the fight between two Wing Chun practitioners will be determined by the opponent with the stronger arms, shoulders and chin. However, certain techniques can allow a weaker person to win even if the said person is at a big disadvantage. Strikes that are surprising (for example: a variation in high and low attacks) can throw the stronger opponent off-balance and expose gaps in defense.

Economy of movement
Most Wing Chun attacks take the straightest possible path to the target (usually a straight line) to break the opponent's structure. Wing Chun theory focuses on the opponent's centerline, an imaginary vertical line bisecting the opponent's vitals (throat, heart, stomach, groin). The Wing Chun punch, for example, is delivered centrally from the practitioner's chest rather than diagonally from the shoulders in the first two forms. This helps teach the centerline concept. In the later forms, the punch is delivered diagonally from the shoulder to the centerline. This is because the distance is shorter than bringing the hand from the shoulder, to the center of the chest, and then down the centerline at the opponent.