The P-Value tells us the probability of getting the observed value of the test statistic or a value with even greater evidence against it if the null hypothesis is actually true. What determines whether P-Value is high or low is the significance level which is also denoted as alpha. If the P-Value is lower than the alpha there is a statistically significant difference between groups and the null hypothesis is rejected for the alternative hypothesis. When the P-Value is higher than the alpha the difference between groups is not considered statistically significant and the null hypothesis is not rejected. The smaller the alpha the more stringent the test would be but normally alpha is set at 5%.
Anytime you reject a hypothesis there is a chance you made a mistake. You could have rejected a hypothesis that is true or failed to reject a hypothesis that is wrong.
Type I error is when you incorrectly rejected a null hypothesis (Berkeley, n.d.). For example, a researcher says there is a difference between drugs and their performance when in reality there is not. This can also be considered to be a false positive. The probability of making a type one error is known as alpha.
Type II error is when you failed to reject the null hypothesis when you should have. For example, a researcher says there is no difference between drugs and their performance when in reality there is a difference.