A bond-dependent anisotropic magnetic interaction called Kitaev interaction can be found in honeycomb lattice materials with strong spin-orbit coupling, and has made a profound impact on quantum magnetism research. In particular, alpha-RuCl3 has been heralded as an example of a class of honeycomb lattice quantum magnets called Kitaev quantum spin liquids. In this talk, I will give an overview of recent experimental progress made in the understanding of alpha-RuCl3. The crystal growth, structure, magnetic phase diagram, and magnetic and thermodynamic properties of alpha-RuCl3 will be reviewed first. Then we will discuss our recent resonant X-ray scattering study to determine the magnetic interaction Hamiltonian of this material. In addition to the Kitaev interaction, we found that the symmetric off-diagonal exchange interaction is substantial in this material, which provides a natural explanation for the large anisotropy of the magnetic susceptibility in alpha-RuCl3.