Pileup affects all measurements at the LHC, biasing and smearing all observables. In this talk, I will discuss basic considerations about pileup. I will then review the main method that has been used at the LHC to correct for pileup contamination, namely the area--median method. I will then discuss more recent techniques, putting an emphasis on the associated challenges. As a candidate for improved pileup mitigation, I will discuss the SoftKiller approach.