Punctuated Equilibrium was an idea that was proposed by Stephen Jay Gould and Niles Eldredge.  It was a critique of Darwin’s Theory of Evolution.  Darwin believed that evolution was a slow process that continued on without any sudden changes.  Eldredge and Gould disagreed.  They believed that evolution happened in “fits and starts”—that is, that evolutionary changes sometimes moved quickly, and at other times changes didn’t come at all or came extremely slowly.  When evolutionary changes came slowly or not at all, there was “equilibrium”.  These periods of “equilibrium” were “punctuated” with times of very fast changes or developments; therefore, evolution was not a slow, continuous process.