Explanation of the Charge on Baryons

  Each baryon consists of three quarks represented by small circles within the larger circle.
   The pluses and minuses in each quark represent the charge of each quark where each plus represents 1/3 of a charge and each minus represents -1/3 of a charge.
  To be a baryon, the sum of all the charges has to equal an integer (e.g.,-1, 0, 1 ). In the example, the sum is zero shown in the upper right corner.