Calculus

Calculus - The study of rates of change.

Areas essential to Calculus: (from About.com - Calculus Readiness)

• Real Numbers (Communtative Properties, Associative Properties, Distributive Properties, Density Properties, Identity Properties), Exponents ,and Radicals .
• Factoring.
• Distance Formula (know and apply) and Midpoint Formula (know and apply).
• Quadratic Equations
• Use and apply Trigonometric Formulas.
• A good grounding in Conics.
• Slope of a Line, Rise Over Run.
• Complex Numbers
• A Comfort Level with Matrices and Graph Theory.
• Know Components of a Vector and Polar Conversion Equations.
• An Understanding of Sequences, Series and Probability.

Major fields of Mathematics: (from Wikipedia - Mathematics)

• Logic
• Set theory
• Algebra (Elementary – Linear – Abstract)
• Discrete mathematics
• Number theory
• Analysis
• Geometry
• Topology
• Applied mathematics
• Probability
• Statistics
• Mathematical physics

Reference:

• Calculus Readiness
• Calculus (Wikipedia)
  
• Precalculus (Wikipedia)
  
• Free Online MIT Course Materials | Mathematics