From the introduction:
Skills are one of the most critical aspects of any role-playing system. More than almost any other aspect of a character, they shape the actions the character takes. The "standard" role-playing system has a rigid, limited system for acquiring skills. The total selection of acquirable skills is very limited. Further, there are strict limits on the acquirable skills, dependent on the class of the character.
The NC skill system allows characters to develop skills in a variety of areas; far more skills than a character from the "standard" system can acquire: anything from Weaponless Combat to Cook. At the same time, the skills are linked in such a way that the set of skills a character knows will usually be related to each other, or fall into a few basic groups. You can be a jack-of-all-trades, but will indeed be a master of none.
By spending experience, a character can either gain new skills or improve existing ones. Some new skills will require an initial "entry" roll to determine whether the character is able to gain the skill. The chance of success will depend on some attribute of the character.
Most skills will require practice in the skill to improve, and certain skills will require that particular actions be performed for advancement to be possible.
Skills may be improved faster by finding a mentor proficient in the skill, who can instruct the character. This applies only up to a certain level of ability.
The system is designed so that the referee can design new skills, and easily plug them into the existing framework.