A Punnett Square is a simple diagram used in genetics to predict the possible genetic outcomes of a cross between two organisms. It organizes the alleles contributed by each parent, allowing for a visual representation of how traits may be inherited. Each box within the square represents a potential genotype of the offspring. To create a Punnett Square, the alleles from one parent are listed along the top and those from the other parent along the side. By filling in the boxes, one can determine the probability of different traits appearing in the offspring, helping to understand inheritance patterns.