Punnett squares are diagrams used to predict the genotypes of offspring from a genetic cross or breeding experiment. They were created by Reginald Punnett and involve tracking the inheritance of alleles from parental to offspring generations. The document provides links to online resources for virtual Punnett square labs and assignments to complete for practice with monohybrid and dihybrid crosses, as well as reviewing the laws of segregation and independent assortment.