The territory of a domestic cat will be centered on her own home. Your cat will use scent marks and other marks to define her boundaries. The borders of this territory will not necessarily follow the legal boundaries of your apartment or property. Your cat will define them according to her own ideas. Territories may overlap or may be used in common if many cats live in the same neighborhood. The territory of a cat only remains fixed as long as the cat reigns this area and dominates or expels all intruders. If a stronger cat arrives on the scene, boundaries may have to be redrawn.
Two or more cats in the house will also exhibit territorial behavior. They will take up different territories within the house, which may overlap in areas. The kitchen, for example, may be a point of overlap if this is the place where both cats are fed. As well, they may compete with you for rights to your favorite places, but they won't be too concerned about your rights as head of the household. When a new cat is introduced into the household, give her time to familiarize herself with her surroundings. Give her time to smell the new rooms and to look for possibilities for escape, and offer her the first eye contact with her future four-legged roommates. It is only then that she should meet any resident cats or other animals of the household. In this way, she is more likely to feel less at a disadvantage in the new situation.
Intact male tom-cats will often mark their territory by spraying urine. Neutered cats may also spray urine, but they do so less frequently, and the odor is less pungent. Spraying indoors may occur when cats are trying to establish their social hierarchy in a multi-cat household or if there is a new cat or another animal in the neighborhood trying to take over.
There is usually a pecking order among cats. Dominance can be expressed in different ways and is, like territorial boundaries, not fixed. In multi-cat households it's fascinating to watch the weaker cat take over from the stronger one if she becomes ill or displays some other weakness.
Even a solitary cat in a household may feel the need to establish a territory to increase, for example, her self-esteem or to warn potential rivals.