Cats hate sects, and in the history of feline evolution, there has never been a foothold for them. The door often hinders the cat's patrol activities, making it unable to explore its nest area as it wishes, nor can it be free to return to a safe central base.
Cats need to simply patrol their territory, learn about the activities of other cats in neighboring areas, and then go home with all the necessary information, and humans often do not understand this need of cats: cats like to go out to patrol frequently, but do not want to stay outdoors for a long time unless unexpected changes occur in the local cat's mouth.
This forms the obvious perverse character of pet cats. It wants to run out when it is indoors, and it wants to come in when it is outdoors. If the owner does not install a pet door on the back door of the home, the cat will regularly attract the owner's attention and ask the owner to assist it in completing regular territorial supervision. Continuously viewing the outside world is so important for cats in part because of the scent marker of ten-clock rest system.
Whenever a cat rubs on landmarks within its territory or pees on it, it leaves a personal odor, but the odor will immediately begin to lose its effectiveness. The odor decays at a steady rate, allowing the cat to tell how long ago the cat that left the odor was rubbing or peeing. The reason why cats repeatedly inspect their territory is to seize new and gradually fading odor signals. This job is done and it will again need comfort and safety, so the anxious cat face appears outside the window at once.