Imagine an urn with five different colors of marbles. For each step of the model, one marble is randomly chosen from the urn. The marble is placed back in the urn with an additional marble of the same color. The distribution of marbles in the urn is recorded and the process is repeated 100 times.

Select how many marbles of each color start in the urn and press enter or the run simulation model to see the outcome displayed on the graph.

The model demonstrates self-reinforcing properties of success. Run it a few times and you may be occasionally surprised by the results.
For more information see the wikipedia article on the model.