Morphing is an advanced bio-technological process created by the Andalites, its power made transferable via a small, blue cube called the Escafil device. Morph-capable beings are capable of 'acquiring' the DNA of any animal, allowing them to physically 'morph' into that animal at will.  Morphing uses cascading cellular regeneration, combined with a variant on Z-space technology, in order to make the transformation.
It typically takes about two minutes to morph, though, this varies depending on the user's focus. If one stays in morph longer than two hours, they becomes trapped in that morph, turning into a nothlit. A nothlit can never return to their original form, though in rare circumstances, they may regain their morphing ability from the Ellimist. While in morph, one is still capable of thought-speak. One also has the drawback/advantage of being confronted with the morphed creature's mind and instincts. This proves very useful for using the body and functioning at its peak, but it also proves to be a struggle when you first enter the morph, and also whenever you go against the creature's instincts (eg: a cat hunting a mouse, a predator wanting to hunt, etc). Note that these two minutes for the morph will be counted as your morph time.
Morphing technology is still new, and very unpredictable. Any damage or injury sustained while in the morph will be healed, as the body is based purely on the DNA. Therefore, similar to injuries, things such as surgeries and implants will not affect the morph. Some, like the Animorphs have found success in integrating very small amounts of skintight clothing into morphs. Usually this would consist of things such as leotards or similarly tight clothes, and nothing like coats or even shoes.
There are several other known quirks to morphing. First, an estreen is a person naturally talented at morphing. This type of person can usually morph at an accelerated rate, control instincts better, and also control the normally chaotic process of morphing itself.
Another morphing-related problem is caused by emotional stress, which disrupts the person's natural ability to concentrate during the morph and causes them to morph at least two animals at once, resulting in bizarre combinations of bodyparts that rarely flow together very well.
Then there is the issue of Z-space. When one morphs a being smaller than themselves, the extra mass is extruded into Z-space. In the rare event that a ship would pass by, they would be drawn into it and likely evaporated by the ship's force field. According to a recently documented occurrence, the being's consciousness is pulled back to the mass in Z-space, rather than staying with the morphed body as usual. It used to be thought that the mass would be unorganized, random blobs, but it is now known, or at least conjectured, that the mass is in fact fully formed and proportioned. Should the mass survive somehow, it is subject to a 'snap-back' effect called a Residiual Flux-field, and causes the consciousness to return to the original body, with no time passing whatsoever. There is the issue of the nothlit, one trapped in morph by staying in morph for longer than two hours, as previously mentioned.
Finally, there is the effect during the acquiring process itself. In order to acquire a creature, one must make physical contact with the subject in question. The acquiring process demands concentration and a break in concentration will abort the process. During the process, when the animal is being 'acquired', it falls into a trance and becomes docile, similar to being tranquilized. This effect lasts for mere seconds after the acquiring is completed, so for it to be advantageous, it would have to be used quite carefully. Rarely, the acquiring process has no effect whatsoever, and the animal is not affected. This is very rare, however, and not usually an issue. There is no known limit as to how many morphs one can possess, though one would assume by means of its storage that the number would be quite high.
It was speculated that the DNA is stored inside the body within a small, molecular sphere, supercooled to sub-zero temperatures, lying dormant until called upon for a morph. Therefore, the body would be capable of holding much more than would ever be conceivably necessary to a morpher. Whoever speculated this is wrong, however, as it is stated many times, most notably in Book #49: The Diversion, the DNA simpily floats around in the blood system until called forth by the morphing technology.
It is occasionally mentioned that the Animorphs use morphing technology in a much different fashion to that of its Andalite creators. Where the Animorphs amass a vast arsenal of situational morphs and use them as weaponry, Andalite morphers often spend their lives mastering one or two morphs for the purposes of subterfuge.
As a final note, a particularly useful aspect of morphing is the Frolis Maneuver, in which one combines the DNA of several samples from the same species, to create a new being for a morph. This could be used, for example, to avoid having an exact duplicate of a human when in morph, should one be morphing a human.
Rules of MorphingEdit
They are seven main rules to morphing which cannot be disobeyed.
Rule 1: There is a time limit equal to two Earth hours. If one stays in morph for more than two hours, they are stuck, becoming a Nothlit. A Nothlit can never return to their original form, or morph, ever again.
Rule 2: You cannot 'acquire' a morph directly from another person's morph or acquire a morph while you are in a morph.
Rule 3: You cannot morph directly from one morph to another, you must return to your natural form first.
Rule 5: 'Morphing-sickness' is a rarely documented case when a morpher is allergic to DNA they have acquired. They become nauseous, and are prone to involuntary bouts of morphing when under stress. After a certain amount of time, between a few days and a week, one 'burps' the DNA so to speak, forcing out the creature in its entirety. Through the cascading cellular regeneration, an entirely new animal is created, and expelled from the morpher's system. They are then faced with the problem of having the animal there in the first place, should this animal prove to be dangerous. This process of expelling the DNA is called hereth Illint, translating from the Andalite tongue as "burping DNA".
Rule 6: When one morphs a being smaller than themselves, the extra mass is extruded into Z-space. In the rare event that a ship would pass by, they would be drawn into it and likely evaporated by the ship's force field (Also, if one was to morph a form larger than one's self, the extra mass would likely be drawn from Z-space).
Rule 7: One can morph any living multicellular animal whose DNA they have acquired. However, one cannot morph a plant, a dead animal, inanimate objects (like chairs), or bacterium.
Finally, there are some pros and cons about morphing: