The probability associated with an obtained statistic, such as an F-ratio. If the -value is less than the significance level, then the result constitutes evidence against the null hypothesis.
The probability of getting the observed value of the test statistic or more extreme when H0 is true. We reject H0 if p is sufficiently small, sometimes smaller than a predetermined significance level (e.g. 5% or 1%).
The smallest significance level for which the null hypothesis would be rejected, based on the data that was actually observed.