Usually, cats are seen as being lone creatures, independent, self-sufficient, mysterious and sometimes jaded and ignorant. Even most cat owners prefer a single cat in their home. What people don't know is that cats are not quite solitary. Of course, they don't have such strong bonds like wolves have, but they can live amicably in quite large communities.
Large cat communities are represented by feral cats who live in farmyards or large cities, such as Venice or Athens. The primary group unit is mother and her kittens. A few groups of this kind are able to build up a massive cat colony. When you see a cat on its own, it is almost always searching for food or patrolling its territory. Keeping competitors away is one of the main targets, besides food.
If a solitary cat meets another one on its patrol, then a specific category of behaviour types occur. One cat can be dominant and the other one tries to avoid it, both of them try to avoid each other, or both of them can be dominant and confrontations occur. In a confrontation, cats may never make contact, they hiss and spit, arch their back in order to be more impressive, raise the hair of the fur, bristle their tale, vocalize aggressively, until one of them takes off. In a real fight, both cats can be wounded.
There is another type of solitary cat, the one who belonged to somebody but for some reasons, they ended up to live on the streets. They may be disoriented, but they are usually friendly and communicative, and this is why many of them don't stay very much there, as someone takes them home. Maybe because they have some glue attached, you just can't leave them.