The Cardinal Quality, or modality, is called such because it represents the changes in the apparent movement of the Sun. The four signs that have this quality are the places on the Zodiacal wheel where the Sun's apparent motion carries it across the celestial equator going north, to its northernmost point in relationship to the poles of the earth, across the celestial equator going south, and to the southernmost point in its path, respectively.
The signs with this Quality: Aries, Libra, Cancer, and Capricorn, begin the seasons for all those who do not live in Arctic latitudes. Each of them were considered "pivotal" because of the apparent motion of the Sun when it entered them. Consequently, they are considered as being imbued with the quality of leadership.
In some parts of the world, the word "moveable" is used to describe this Quality, because those who observe the Sun's movements see a change in direction whenever it reaches one of these places.
People who have a predominance of the Cardinal Quality tend to be self-motivated and are always prepared to get things going. Whatever they are involved in is usually something that they initiated; they are not the type of folks to wait around until something new happens.
Cardinal people usually are ambitious, even though some do not display the ambition outwardly; that depends on which of the Four Elements dominates the horoscope. They are all driven, and sometimes are so ready to take action that they assume a leadership role when it isn't necessary. This can give some people the impression that those with many horoscope factors in Cardinal Signs are bossy or domineering.
Along with ambition and an instinct for leadership, Cardinal people tend to be winners. That's not because they are lucky, but because they subconsciously want to win and develop themselves to think like winners on a very deep level.
The Modalities or Qualities are not relationship factors on their own, they describe how the different Elements operate. In other words, one cannot say that a Cardinal Person is more compatible with a Fixed or Mutable person.
When you are interested in a person who is dominated by the Cardinal Quality, you know you have connected with someone who likes to be in charge. You may accept or reject their leadership, or you may just tolerate it, depending on your own nature. One thing is certain, however; Cardinal people do not like to wait around, or to spend a lot of time dreaming; they like action, and make sure that others know it.
Don't bore Cardinal people with unimportant details; they tend to like the facts and work with them. Some are good listeners and some are not; very few of them are prone to being overly sympathetic, or for putting others' problems above their own. They all like having something to do; it's a very unhappy Cardinal person who is told to wait, or to sit back and let someone else take care of business.
Cardinal people are also very self-directed and don't like being told what to do. They do not respond well to the demands of others, and resent being given an ultimatum. They do like to negotiate with others, but their goal is usually to win, and not to compromise.
In order to understand the meaning of the Cardinal Quality better you can read our article on the Cardinal Signs or read about the individual signs that have this quality: Aries, Libra, Cancer, and Capricorn.