Note: This article deals with very general concepts of existence. It's difficult to find a good term for that existence; 'stuff' doesn't quite do it justice. So, for the purposes of this article the term 'objects' is used to refer to anything that has a physical existence; atoms, rocks, black holes, etc.
The term "focus" is used to refer to the ability some beings have of 'focusing' their willpower in such a way as to cause a fundamental change in the universe itself. Beings who can use Focus are able to force the Universe to change in advantageous ways. They frequently manifest as specific abilities or "powers" that appear almost magical in nature.
The most fundamental force in the universe is willpower. It is what drives all the other forces of nature; gravity, the strong and weak nuclear force, the very existence of quantum particles themselves; all are governed by the laws of willpower. The universe exists simply because it has enough willpower to exist. The laws of physics and the very fabric of existence itself all flow from the Universe's immense will.
Willpower is not to be confused with sentience or self-awareness. It's better to think of it as 'the inertia of existence'. A boulder exists as it does, where it does, simply because it has enough willpower to exist. If you want it to cease to exist, you must apply enough willpower to overcome it's inherent willpower. (There are other ways one could do this, but this is the most basic.) Generally, that takes more willpower than a single individual can be mustered; it's much easier to effect the boulder in other ways, such as making it lighter, or moving it aside, or making it explode.
The fundamental tenants of willpower are:
These tenants have some interesting implications. First, the longer an object has existed, the more willpower is required to destroy it (exponentially so). Next, you can create an object that has a long history and is already very old; but the willpower required to do so is astronomical. Yet, with sufficient willpower, you can reshape and reorder the universe to your liking. Events of the past, while immutable in a direct sense, can be rearranged. While strict time travel is not possible, one can reorganize the universe such that you existed in the past, and modified events by your presence. (However, since an object's existence must be continuous, the further back in time you would recreate yourself, the older you would now be, though as long as you returned yourself to the present, you would only age by the time "spent" in the past. The continuity rule also avoids the common "paradoxes". If you would erase yourself from existence, then you must be explicit.)
Some sentient beings are able to manipulate and channel willpower (either from themselves or from the universe itself). This ability is called 'focus'; it is quite literally a being focusing their willpower to effect a change. The greater the ability to focus, the less willpower is require to effect the desired change. (It is important to be clear that this is not "focusing" as in mental concentration, but rather focusing, like focusing a beam of light.)
Only sentient beings have the ability to use Focus. While objects may enhance one's ability to Focus, they cannot grant it. The ability to use Focus is intrinsically tied to sentience, though simply having sentience does not mean you have Focus. (It should also be noted that objects may grant willpower, but they cannot grant the ability to focus to a sentient that does not already have it)
The ability to focus seems to have more to do with one's race, than anything about the individual. Some races, like The Overseers, are nearly universally predisposed to Focus, while in others only a small percentage of members can use Focus. It's actually more common that no members of a race can use focus. There's no explanation for why Focus appears to be a property of race. Some races, like The Grey believe that the universe created races as a way of understanding itself. Those races who can use Focus, therefore, would be special parts of the universe that allow it to explore it's own nature. The Overseers, however, believe that it's more related to biological makeup and evolution than some inherent choice of the Universe. They cite their creation of the Sooni as support for this.
Some races, like humans, generally only have the ability to use Focus on a subconscious level. Using Focus generally (but not always) requires concentration on the user. However, in very rare cases, focus users are able to effect change without concentrating. Humanity is a rare instance of a race where a majority of their race can do this, but cannot (necessarily) also ever learn to wield Focus consciously.
(See: Humanity for more details.)
A common experience Humans have, is looking for an item, not be able to find it, and accidentally using Focus to manifest it where they believed it should have been. While rare, most humans fundamentally understand this example.
This example illustrates how a basic application of Focus can be used to do something as simple as change an item's location. A more advanced application could cause the object to fly to your hand, as opposed to appearing someplace unseen. This also illustrates a fundamental of Focus use; the more sentient creatures something affects, the more difficult it is to overcome their natural will for the universe to remain unaltered. This has the interesting effect that it's significantly easier to perform feats of Focus alone and unseen.
Many races have the concept of 'an act of will'. It's what they use to describe the act of gathering willpower and using it to cause an effect; generally a change in their own mental state. Sometimes, however, these 'acts of will' are also doing things like pushing themselves beyond their physical limits, or clashing with external forces. This is a very rudimentary analog of Focus. Most races don't have the ability to go beyond this, actually concentrating their willpower, and applying it to effect the change they desire, but the mental act is very similar. Among some races that are more inclined to Focus, like humanity, their 'acts of will' are in fact actual applications of Focus, but on a more subconscious level.
In order to Focus, a sentient first gathers willpower either from themselves, or from objects around them. This willpower is then concentrated inside the sentient. The more well trained the Focus user, the stronger the concentration. This willpower is then released and applied towards the desired effect. The more exact and focused the desired effect, the more effective the willpower will be when applied to it.
For example, let's say a Focus user wishes to change the color of a piece of cloth from blue to red. If they simply attempt to change the color to "red", it will take more willpower than if they wanted to make it a particular shade of red. The more specific the desired change, the less willpower it takes (in general) to make it happen.
This effect can be misleading, however. Specificity, while having the benefit of raising the effectiveness of willpower applied (therefore requiring less) can also require a more substantive change, therefore requiring more willpower than if it was less specific.
Here's another example. Let's assume again that a Focus user wishes to change the color of a piece of cloth. Instead of simply wanting to change it to "red", they desired to change it to a "worn, faded red cloth that has seen much use over many years". This is much more specific, however it would cost much more willpower to change. The reason is that the details -making the cloth worn and faded- imply adding a history to the cloth, which will require exponentially more willpower to reorder the universe in such a way to accommodate it. In fact, it is likely to cost so much willpower that it would simply fail.
A seasoned Focus user, however, would likely amend the desire such that the cloth "took on the appearance of being worn and faded, but was still, in fact, the same cloth". Those additional details circumvent the requirement of a long history, while maintaining (and in fact increasing) specificity.
This illustrates a fundamental property of Focus users; the more they train and the more experience they become, the more efficient they are at using their willpower. They do not gain any additional access to willpower that a novice would not also have; rather they can simply concentrate it more, and apply it more efficiently. This is often expressed with the analogy of a blade; a sharpened blade has no more metal in it than an unsharpened on (and in fact it may have less) but the metal has been honed such that it can apply the force it is swung with in a much more targeted way.
As with anything, there is a practical limit to how much willpower a Focus user can wield. With training, they can increase their skills to be able to handle more, but there are other limiting factors. First, and most limiting is the fact that all beings have an inborn total amount of willpower, and no matter how good they become at harnessing that, the are limited to whatever willpower they have. While it is possible to borrow willpower from objects (often destroying them in the process, it is rare that a sentient being can exceed their total willpower by enough to make the destructive nature of borrowing willpower worth it.
This has lead some Focus users to experiment with ways to tap into alternative sources of willpower. Pockets of willpower, known by the Overseers as 'jyse', have been used as a way for a Focus user to temporarily tap into astronomical amounts of willpower. These experiments are often disastrous, as the user finds themselves unable to maintain control as their wills are overridden by the more powerful willpower from the source they were 'borrowing' from. (See the Jyse War.)
An advanced technique some Focus users employ is 'channeling'. It involves amplifying their effective willpower by focusing their will on making a greater willpower will the effect they desire. Originally developed as a method for coordinating change, it was never found to be effective. However, if channeling is applied to non-sentient objects containing large amounts of willpower or jyse, the effects can be stunning.
It is possible for Focus users to coordinate with each other in order to achieve a common goal. However, they must either have a shared understanding of the goal, or be willing to give their willpower to a single Focus user. Such submission is dangerous, however, as their will is temporarily subsumed by the one their giving their power too. That individual may use their will as they see fit, or tap into enough to be harmful or deadly to the one giving of themselves. It's much safer to simply try to share the understanding, though the outcomes are rarely perfect.
Because it is easier to apply Focus to oneself, the most common Focus derived abilities are all self oriented. Many of these can be applied to others, but that increased the difficulty significantly.
The most common form of Focus use is increasing one's physical abilities. Moving faster, increasing one's strength, increased mental acuity, etc. Almost all Focus users have these abilities, but the amount they can increase any particular attribute depends entirely on both the individual and their understanding of their own limitations. The more they understand their own natural abilities, the more specific they can be about the increase they are trying to achieve.
All types of healing (both to oneself and others) are possible with Focus. Simply increase one's healing rate is easiest; resisting poison or disease is next in difficulty, and regrowing lost limbs or repairing permanent damage is the most difficult.
Other forms of healing (for example, willing a shot to have missed, instead of hit) are possible, but very rare.
Resurrection is possible, including of oneself. However, it's very difficult and you must have an extraordinary amount of willpower intrinsically to be able to resurrect oneself. Resurrecting others, is actually easier simply because you are not currently dead while trying to do so.
There are, however, some limitations. Resurrection is often just returning the body to life. There is a 'fundamental essence' that is often lost during death. This essence is not well understood; some believe it to be a special type of willpower that sentient beings posses, and is lost after death. Others believe it to be a form of 'soul'. Returning an individual to a state before they died can be an astronomical feat of willpower, but it can be done.
While minor teleportation of a non-sentient object a short distance is something most Focus users can do, teleportation of sentient entities (or objects containing them) is something only Focus users talented with teleportation can do. Theoretically, the only limit to this power is the amount of willpower the user can tap into; in reality anything more than self-teleportation is difficult.
Extremely powerful Focus users have been able to teleport large groups, or even a single ship. Whole fleets have been done with the coordination of several Focus users.
Just like with physical martial arts, there are many schools of focus abilities. These are collectively known as "disciplines". Some are able to be learned with practice, while others seem to be innate gifts.
(See Focus Disciplines for more information.)