A rational blowdown surgery initially introduced by R. Fintushel and R. Stern and later generalized by J. Park is one of the simple but powerful techniques in study of 4-manifolds topology. Note that a rational blowdown surgery replaces a certain linear chain of embedded 2-spheres by a rational homology 4-ball. In particular, a rational homology ball is a key ingredient in the construction of exotic smooth, symplectic 4-manifolds with small Euler characteristic and complex surfaces of general type with $p_g = 0$. It also plays an important role in $\mathbb{Q}$-Gorenstein smoothings and symplectic fillings of the link of normal surface singularities.

In this talk, I review what we have obtained in study of 4-manifolds using a rational blowdown surgery in various levels. And then, I'd like to discuss some open problems in related topics.