A vertical asymptotes is a non-removable discontinuity; that is, there is no way to re-define the function such that the function will continuous at that point. On other other hand, holes are removable discontinuities; that is, there IS a way to re-define the function such that it will be continuous at that point. If you know what limits are, think of them like that.
A vertical asymptote occurs in a rational function if the denominator is made zero at a certain value of x, but the numerator is non-zero. A hole occurs when a value of x causes both the numerator and denominator to be zero at the same time.
A vertical asymptote occurs in a rational function if the denominator is made zero at a certain value of x, but the numerator is non-zero. A hole occurs when a value of x causes both the numerator and denominator to be zero at the same time.