Sir Ronald Fisher introduced the p-value in 1925 to measure the evidence against a null hypothesis based on experimental data. However, p-values are often misunderstood. A p-value does not represent the probability that the null hypothesis is true or false. It represents the probability of obtaining results as extreme or more extreme than what was actually observed, assuming the null hypothesis is correct. Lower p-values provide stronger evidence against the null hypothesis, but do not prove it to be false.