Department Colloquium Link: http://myumi.ch/GkgBm

Nucleons (protons and neutrons) are the building blocks of atomic nuclei and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying its internal structure, there are still a number of puzzles surrounding the proton such as its spin and the charge radius. The proton charge radius puzzle developed more than 10 ten years ago refers to a discrepancy of 5-7 standard deviations between the ultrahigh precise values of the proton charge radius determined from muonic hydrogen Lamb shift measurements and the CODATA values compiled from electron-proton scattering experiments and ordinary hydrogen spectroscopy measurements. In this talk following a short introduction, I will focus on the proton charge radius puzzle, the latest experimental results, especially those from the PRad experiment at Jefferson Lab, and the future outlook with the PRad-II experiment.