The study of Parton distribution functions (PDFs) is necessary to understand the internal structure of protons and other hadrons. PDFs describe how the proton's momentum is distributed among its constituent quarks and gluons, and they are essential inputs for making predictions at particle colliders like the Large Hadron Collider (LHC). Over the years, several global PDF sets, viz. CTEQ/CT, NNPDF and MSTW/MMHT/MSHT collaborations have been developed based on a variety of experimental data and theoretical frameworks. This book explores the comparative graphical studies of global PDFs and offers valuable insights into the similarities and differences in their results, and the uncertainties associated with their predictions. The plots of the distributions of different parton species as functions of the momentum fraction at various energy scales allow for visual review of these comparisons between the PDF sets.