A birth chart has 360 degrees, as do all circles, and there are various ways to divide circles. In Astrology the circle is divided into 12 parts called, "houses" which consist of (more or less than) 30 degrees each. This division begins at the point of observation (birth place) and is considered a division of the earth projected outward to the ecliptic. I like to picture it as if you cut a pie into 12 pieces and those cuts project outward into space. On the birth chart the ecliptic is represented by the outer circle with the Signs of the Zodiac which are located in space. The Zodiac is a point in space where it appears that the Sun travels around the earth, but we all know who's moving around whom... If you were born on the equator, the houses would be naturally equal, but the further North or South of the equator you are born, the more distorted the houses can be. At the North or South Poles you may only have 6 houses all squished together, but you will always have 12 Signs. So, latitude is important in determining the Houses. Below are my charts in different displays. The first shows equal houses (not to be confused with the equal house system which is used in Great Britain). Next to it shows unequal houses. The Astrodienst and the Astrolabe charts both show unequal houses. For simplicity, I like the equal house chart although it is not the true perspective of the latitude of one's birth. If you click on the Astrodienst or the Astrolabe charts, you can go to their websites and get your free chart as well as see what they have to offer. Both sites are very reputable and excellent.