The famous result given by Muckenhoupt in 70s described the class of the functions, so-called Ap weights, that ensure the boundedness of Hardy-Littlewood maximal operator on weighted Lebesgue spaces equipped by them. In this lecture provide the short list of basic properties of these weights.
Next, we introduce one-sided Ap weights, show the similarities and differencies with the original ones and discuss their importance. As a conclusion, we provide some application of one-sided Ap weights in ergodic theory.