The careful determination of parton distribution functions (PDFs) is an important task for the calculation of observables in hadron beams. At the same time, indirect searches of new physics are carried out in the context of the Standard Model Effective Field Theory (SMEFT) and can be observed as subtle deviations from the SM. In this topical seminar, we will discuss the PDF-SMEFT interplay, in particular in the context of their simultaneous determination and evolution equations.