Aikido techniques

Aikido techniques are frequently referred to as waza 技 (which is Japanese for technique, art or skill). Aikido training is based primarily on two partners practicing pre-arranged forms (kata) rather than freestyle practice. The basic pattern is for the receiver of the technique (uke) to initiate an attack against the person who applies the technique—the 取り tori, or shite 仕手, (depending on aikido style) also referred to as (投げ nage (when applying a throwing technique), who neutralises this attack with an aikido technique.
Both halves of the technique, that of uke and that of tori, are considered essential to aikido training. Both are studying aikido principles of blending and adaptation. Tori learns to blend with and control attacking energy, while uke learns to become calm and flexible in the disadvantageous, off-balance positions in which tori places him. This "receiving" of the technique is called ukemi. Uke continuously seeks to regain balance and cover vulnerabilities (e.g., an exposed side), while tori uses position and timing to keep uke off-balance and vulnerable. In more advanced training, uke may apply reversal techniques (返し技, kaeshi-waza) to regain balance and pin or throw tori.
Ukemi (受身) refers to the act of receiving a technique. Good ukemi involves attention to the technique, the partner and the immediate environment - it is an active rather than a passive "receiving" of Aikido. The fall itself is part of Aikido, and is a way for the practitioner to receive, safely, what would otherwise be a devastating strike or throw (or joint lock control) and return to a standing position in one fluid movement. The person throwing (or applying other technique) must take into account the ukemi ability of his partner, as well as the physical space: walls, weapons (wooden tantō, bokken, jō) on the tatami, and the aikido practitioners nearby.
Uke must attack with a strength and speed appropriate to the skill level of the tori; in the case of beginners, this means an attack of far less severity than would be encountered in a real-life self-defense situation.
Aikido techniques are usually a defense against an attack; therefore, to practice aikido with their partner, students must learn to deliver various types of attacks. Although attacks are not studied as thoroughly as in striking-based disciplines such as karate or boxing, "honest" or "sincere" attacks (a strong strike or an immobilizing grab) are needed to study correct and effective application of technique.
Many of the strikes (打ち, uchi) of aikido are often said to resemble cuts from a sword or other grasped object, which indicates its origins in techniques intended for armed combat. Other techniques, which appear to explicitly be punches (tsuki), are also practiced as thrusts with a knife or sword. Kicks are generally reserved for upper-level variations; reasons cited include that falls from kicks are especially dangerous, and that kicks (high kicks in particular) were uncommon during the types of combat prevalent in feudal Japan. Some basic strikes include:
Beginners in particular often practice techniques from grabs, both because they are safer and because it is easier to feel the energy and lines of force of a hold than a strike. Some grabs are historically derived from being held while trying to draw a weapon; a technique could then be used to free oneself and immobilize or strike the attacker who is grabbing the defender.
When all attacks are considered, aikido has over 10,000 nameable techniques. Many aikido techniques derive from Daitō-ryū Aiki-jūjutsu, but some others were invented by Morihei Ueshiba. The precise terminology for some may vary between organizations and styles; what follows are the terms used by the Aikikai Foundation. (Note that despite the names of the first five techniques listed, they are not universally taught in numeric order.) Several techniques (e.g. the "drop" throws) are also shared with judo, which can be considered a "cousin" of aikido due to their shared jujutsu background.
Aikido techniques can be broadly classified into two groups, immobilizing techniques (固め技, katame waza) and throwing techniques (投げ技, nage waza).
The Yoshinkan school retains these Daitō-ryū Aiki-jūjutsu terms for the "first" through "fourth" techniques:
Breath throw (呼吸投げ, kokyū-nage) refers to a class of techniques that centre on the union of breathing and throw, that generally do not end in joint locks like the immobilising techniques. The names of specific techniques may vary across organizations and dojos, but they begin with uke coming from the rear and blocking one or both tori's wrists; at their heart there are the two parts of breathing: inspiration and at the same time an elbow-arm ascending arc which uke must follow, expiration(and a lateral displacement) with the arc now descending, sending uke in the resulting vacuum. Different types of kokyū-nage may include:
Aikido makes use of body movement (tai sabaki) to blend with uke. For example, an "entering" (irimi) technique consists of movements inward towards uke, while a "turning" (転換, tenkan) technique uses a pivoting motion. Additionally, an "inside" (内, uchi) technique takes place in front of uke, whereas an "outside" (外, soto) technique takes place to his side; a "front" (表, omote) technique is applied with motion to the front of uke, and a "rear" (裏, ura) version is applied with motion towards the rear of uke, usually by incorporating a turning or pivoting motion. Finally, most techniques can be performed while in a seated posture (seiza). Techniques where both uke and tori are sitting are called suwari-waza, and techniques performed with uke standing and tori sitting are called hanmi handachi.
Thus, from fewer than twenty basic techniques, there are thousands of possible implementations. For instance, ikkyō can be applied to an opponent moving forward with a strike (perhaps with an ura type of movement to redirect the incoming force), or to an opponent who has already struck and is now moving back to reestablish distance (perhaps an omote-waza version). Specific aikido kata are typically referred to with the formula "attack-technique(-modifier)". For instance, katate-dori ikkyō refers to any ikkyō technique executed when uke is holding one wrist. This could be further specified as katate-dori ikkyō omote, referring to any forward-moving ikkyō technique from that grab.
Atemi (当て身) are strikes (or feints) employed during an aikido technique. Some view atemi as attacks against "vital points" meant to cause damage in and of themselves. For instance, Gōzō Shioda described using atemi in a brawl to quickly down a gang's leader. Others consider atemi, especially to the face, to be methods of distraction meant to enable other techniques. A strike, whether or not it is blocked, can startle the target and break his or her concentration. The target may also become unbalanced in attempting to avoid the blow, for example by jerking the head back, which may allow for an easier throw. Many sayings about atemi are attributed to Morihei Ueshiba, who considered them an essential element of technique.