Differential Calculus is a generalization of the "slope" concept in algebra. It deals with slopes or *rates* of all kinds. Any time you have a problem that changes values over time, you will often want to know what that rate of change is in any given situation. This rate of change is called the "derivative."Although this may not seem like that profound or important a notion at first, think of it this way. Dollars per hour (wages), miles per gallon (gas mileage), kilowatts per hour (energy usage), megabits per second (bandwidth), etc. are all rates, or derivatives. To predict future yields or calculate using these rates, you need differential calculus.
