Summary of solid pile-up around the snow line. Icy pebbles, which uniformly contain micron-sized silicate dust formed at the outer disk, drift inward due to the gas drag. Pebbles sublimate through the passage of the snow line (Sect. 3) and silicate dust is released together with the water vapor. Silicate dust is well coupled to the gas and the radial drift velocity significantly drops from that of pebbles. This causes so-called “traffic-jam” effect and the dust piles up inside the snow line. A fraction of water vapor and silicate dust diffuses from inside to outside the snow line recyclesonto pebbles via the recondensation and sticking, causing a local pile-up of pebbles just outside the snow line. Midplane concentrations (i.e., midplane solid-to-gas ratio) of pebbles and silicate dust strongly depend on their scale heights. Near the snow line, the scale height of silicate dust is the minimum as the dust is released from pebbles whose scale height is much smaller than that of the gas. This causes the maximum midplane concentration of silicate dust just inside the snow line. Significant midplane concentrations of silicate dust and/or icy pebbles would cause gravitational instability and/or streaming instability, forming rocky and/or icy planetesimals, respectively (Sect. 5).