At one point, pretty much every unarmed system that used grappling in Japan was referred to as some form of jujutsu. This means that the name itself is pretty much generic, like kung fu. Below are the major categories of techniques that are traditionally recognized in Japanese systems. Again, these are just to organize things and many specific techniques can fall under multiple categories. Various jujutsu systems have a different emphasis than another, but all of these types of techniques are found in every system that calls itself jujutsu.
This includes not just hitting with the hands, but elbows, feet, knees even the entire body and anything else handy that doesn't have an edge. Most jujutsu styles do not have striking similar to karate or taekwondo. There are no fancy leaping kicks or other acrobatics. The reason for this is historical. The people who developed this were samurai so that they wore armor (and excellent armor too, I might add). A "one punch knockout" is virtually impossible against an un-armored opponent anyway, and doubly so against a samurai, so there was no incentive to develop powerful strikes. This is not to say we won't hit you constantly, but we are more interested in moving the body in certain ways to control it, rather than inflicting massive damage. On the plus side, a small person can apply this striking to a much larger attacker with good effect.
These are techniques that attack the joints directly, such as joint locks and breaks. These also include bone breaking techniques. Jujutsu has some of the most effective and elegant joint techniques of any martial art and these form the core for it. Again the reason is historical. A samurai armed with a sword is a fearsome opponent and of the best ways to defend oneself at close quarters is by rendering the attackers joints immobile at the least and possibly unusable.
Another cornerstone of jujutsu is its throwing techniques. Many systems have throwing, but these tend to be more like quick takedowns or dumps. Jujutsu is again famous for astonishingly powerful throws and the intent of many of them is to kill a fully armored opponent. I am quite convinced they would do this or at the least severely disable one. As such, we have a strong emphasis on falling (see ukemi-te) and safety in general. Generally, one throws only when the opponent is in position for this and to avoid being taken to the ground. This is summed up in the statement that we tend to throw to avoid ground-fighting.
This covers all aspects of escaping, rather it be from a grab or other hold to extracting oneself from a dangerous situation.
This class of techniques is for robbing your opponent of effective movement by holding some part of him. These also include restraining techniques in which the opponent is on the floor. Many traditional techniques end by holding the opponent on the floor using the defender's body weight and legs or feet, thereby leaving the defender's hands free.
This class of techniques includes choking and squeezing or wrapping techniques to control an attacker. Grapples as a prelude to throwing are in this goup. Note: we do not apply attacks to the windpipe in our chokes. This is because these have a very real chance of killing the opponent in a street encounter unless the defender is extremely proficient. Moreover, no training is needed to realize you are being throttled, and this can elevate a simple restraining situation into a frantic life or death struggle. We use what are euphemistically termed lateral neck restraints (LNRs) which constrict the blood supply to the brain. Effectively, this is like applying a tourniquet to the neck. Since air flow is unimpeded, attackers rarely realize they are the victim of this technique and simply pass out. Many police forces are authorized to use these, but not windpipe chokes, it should be noted.
One of the core concepts of all martial arts. For us it does not merely mean how the defender moves, but how the attacker moves once you are engaged. There are several ways of moving. The basic footwork is very simple, being simply irimi, entering, kaiten, turning or tenkan, a mixture of the two. Applications of these are done at each level. Jujutsu is a positional fighting system, by that I mean that where you are in relation to your attacker determines what options you have. Body movement is therefore the cornerstone of the entire art.
The Japanese word uke means "to receive", hence the person receiving a technique is referred to as the uke. The defender is referred to as the tori. This also applies to stopping techniques thrown at the defender, such as punches and specifically it refers to falling from throws. Colloquially, most people use it as a synonym for falling, but every technique has a way to receive it with at least a modicum of safety and part of the instruction of a technique is it ukemi. A distinction should be made between receiving a technique and avoiding one. Throwing is a good example, in that if one can stop being thrown that is usually good, but this is not teaching how to receive the technique. For that falling is required and if one does not have falling ability then one has a large hole in security.