Significance tests help us determine if there is a real difference between groups in a population. By comparing sample data to what we would expect if there was no difference, we can see if the evidence supports our idea. A small P value (usually less than 0.05) means strong evidence against the idea of no difference. The smaller the P value, the stronger the evidence. If the P value is high, it means weak evidence against the idea of no difference. This doesn't prove there is no difference, just that we couldn't detect it with our sample size.