What is the ‘plum pudding’ model of an atom?

This model was proposed by JJ Thomson, who had also discovered the electron. It was put forth before the discovery of the nucleus. In this model, the atom is a sphere of positive charge, and negatively charged electrons are embedded in it to balance the positive charge. The electrons are like plums in a pudding. This model was rejected when Rutherford performed the alpha particle scattering experiment and put forth his model of the atom, which was like our solar system, with electrons revolving around a positively charged, dense nucleus.