The probability density function (PDF) is an equation that represents the probability distribution of a continuous random variable. The PDF curve indicates regions of higher and lower probabilities for values of the random variable. For example, for a normal distribution, the highest PDF value is at the mean, and lower PDF values are in the tails of the distribution.
For a discrete distribution, such as a binomial distribution, you can use the PDF to determine the probability of exact data values (also called the Probability Mass Function or PMF).
If you want to know the cumulative probability for any x-value, use a Cumulative Distribution Function (CDF).
If you want to determine the x-value for a specific cumulative probability, use an Inverse Cumulative Distribution Function (ICDF).