A stasis field is a region where a stasis process is in effect. Stasis fields in fictional settings often have several common characteristics. These include infinite or near-infinite rigidity, making them "unbreakable objects", and a perfect or nearly-perfect reflective surface. Most science fiction plots rely on a physical device to establish this region. When the device is deactivated, the stasis field collapses; that is, the stasis effect ends.
Time is often suspended in stasis fields. Such fields will thus have the additional property of protecting non-living materials from deterioration. This time dilation can be, from an in-universe perspective, absolute, so that something thrown into the field, has the field triggered, and after any length of time reactivated, would fly out as if nothing had happened. Storylines using such fields often have materials as well as living beings surviving thousands or millions of years beyond their normal lifetimes. This property also allows for such plot devices as booby traps, containing, for instance, a nuclear bomb. Once out of the stasis field the trap is sprung. In such a situation, it wouldn't do to let the protagonist see what is in the field, so in stories like this, the story line will not allow normal beings to see something protected by a stasis field.
The primary use of stasis fields is essentially the same as suspended animation: to let passengers and cargoes (normally of spacecraft) avoid having to experience extremely long periods of time by "skipping over" large sections of it. They may also be used (such as in The Night's Dawn Trilogy) as protection against the effects of extreme acceleration.
There are real phenomena that cause time dilation similar to a stasis field's. Velocity near light speed or a powerful gravitational field will cause time to progress more slowly. However, there is no known theoretical way to cause such time dilation independent of these conditions.
Stasis in combat 
The noted science fiction author Larry Niven used the concept of stasis fields and stasis boxes to a great extent in a direct or indirect fashion all through his many novels and short stories set in the Known Space series. Niven's stasis fields followed conductive surfaces when established, and the resulting frozen space became a completely invulnerable and perfectly reflective object. They were often used as emergency protective devices. They could also be used to create a weapon called a variable sword, a length of extremely fine wire in a stasis field that makes it able to easily cut through normal matter. For more information, see Slaver stasis field.
A more limited form of stasis field is the "bobble", found in Vernor Vinge's Peace Authority setting. A bobble is always perfectly spherical and exists for a fixed period of time that is set when the bobble is first created. The duration of a bobble effect cannot be changed. Bobble generators were initially used as weapons, removing their targets from the field of combat.
Another example of a stasis field exists in Joe Haldeman's The Forever War, where stasis field generators are carried by troops to create conditions where melee weapons become the only viable means of combat. Inside the field, no object can travel faster than 16.3 m/s, which includes electrons, photons, and the field itself. Soldiers inside the field must be wearing suits with a special coating, otherwise all electrical activity within their body would stop and they would die. In the novel the main character defeats an enemy army which has besieged a small remaining contingent of human troops on a moon by arming a nuclear bomb inside the field and then moving the field away from the bomb. Once the bomb is revealed, its electrical activity resumes, and it promptly detonates. This vaporises the surrounding army, and a large chunk of the ground beneath the field. The soldiers emerge some weeks later to see if their trick worked, and find themselves alone at the bottom of a large crater, their enemy destroyed.
In the computer strategy game StarCraft, the Arbiter unit can, through a combination of Protoss technology and the Arbiter's psionic power, create a stasis field that traps all units in the affected area in blue "crystals" of stopped time, taking them out of the fight and rendering them invulnerable for 30 seconds, thus allowing both offensive and defensive applications.
The game Mass Effect has a biotic power simply called "Stasis" that can trap an enemy in a stasis field rendering them immobile as well as invincible to all forms of damage. The duration of this effect is usually dependent on the user's skill level.
In the Star Wars RPG series Knights of the Old Republic, Jedi who follow the path of the light are able to use "Stasis" powers, using the force to alter time and freeze an enemy in place. Unlike true stasis, this stasis allows external events to affect the victim, meaning that someone held by stasis can be killed while unable to retaliate. The original game also uses a similar effect when Dark Jedi trap party members to engage the player in a duel.
In the 2008 survival horror game Dead Space, players are outfitted with a wrist-mounted tachyon-based stasis module, used to slow enemy Necromorphs to a crawl for a short period of time. Stasis will be used to also slow down items like malfunctioned doors or fast Generator mechanics. Medical use of the technology is later seen in Dead Space 2, with stasis beds; the protagonist had also been kept in stasis for the majority of the time between games.
In the Justice League Unlimited episode "The Cat and the Canary", Green Arrow uses a stunner to put himself into a form of stasis while fighting Wild Cat. This was an attempt to end Wild Cat's cage fighting career by falsely convincing him he killed Green Arrow during their fight.
In the Invader Zim episode "Walk For Your Lives", Zim creates a time stasis field and uses it on Dib as an experiment to show to the Tallest, as a result Dib can only move very slowly. Also produced is an explosion, which is also exploding very slowly, Zim decides to throw Dib into the explosion to cause it to speed up. The explosion then explodes at normal speed.
The Space themed MMO Eve Online features a weapon called a stasis webifier. When activated against an enemy ship it reduces the target's speed, making them easier to hit and keep in range. The weapon affords no protection to its target, and multiple 'webs' can be used on a ship at once, effectively stopping it dead.
In Half Life, the protagonist Gordon Freeman is put into a state of Stasis after a brief discussion with the G-Man. A similar incidence happens to Adrian Shepherd at the end of Half Life: Opposing Force when the G-Man puts him into a state of stasis "for further evaluation".
In Project Eden one character is frozen in stasis for 15 years. Stasis can also be used offensively to slow down enemies.
See also Quasis.
Stasis as an Illness 
In the anime Please Teacher!, stasis, known in the series as "standstills," is an illness affecting Kei Kusanagi and Ichigo Morino, and is triggered by a sudden attack of emotional stress. In a sense this illness freezes them as to time and appearance. Kei, despite being in high school, is actually 18 years old; Ichigo, his classmate, is actually 21.