Topics and problems on favorite sites of random walks

In this article, we study special points of a simple random walk and a Gaussian free field, such as (nearly) favorite points, late points and high points. In section $2$, we extend results of [19] and suggest open problems for $d=2$. In section $3$, we give a survey on the geometric structures of (nearly) favorite points and late points of a simple random walk and high points of a Gaussian free field in two dimension.