What is a p-value in statistics?

In statistics, a p-value is used to test the significance of the hypothesis. It indicates the probability that the results were obtained by chance alone. A small p-value indicates that it is very unlikely that the observed result came about by chance. 
However, whether an alternative hypothesis with a p-value of less than 0.05 should be accepted without providing further evidence is controversial. Therefore, to properly quantify the statistical significance of results, contextual factors must also be considered, such as the quality of the measurements, the external evidence, and the validity of the assumptions underlying the data analysis.