Interactive data visualization is widely used by data scientists, but few websites exploring probability distributions use such techniques, and none that we are aware of illustrate the relationships between distributions. Probability Playground (http://www.probabilityplayground.com) was designed from the ground up to be a highly interactive website with a design philosophy focusing on developing intuition through discovery. It provides a consistent interface for exploring 29 probability distributions and their relationships. Unique features include: • Animated loading of examples. • Direct interactive editing of distribution means and variances • Manual and automatic axis scaling • Interactive graphing of distribution relationships • Visualization of the processes generating each distribution Over 150 proofs are also provided for distribution means, variances, and relationships. Students and educators looking for interactive materials to use in their teaching will find Probability Playground a novel contribution for both its scope and degree of interactivity. It provides a valuable addition to the field of statistics and data science education.