The partial symbol is used in calculus to represent a partial differential. The symbols replaces the latin small letter d when referencing partial differenctials in multi-variable calculus. Typically, the symbol is used in an expression like this:
In plain language, this expression represents the derivative of the function with respect to the variable .
The latin letter d.
The derivative of a functin with respect to a variable returns a function that represents the change in the function with repsect to time.