This chapter is concerned with quasi-Monte Carlo rules, i.e., multivariate quadrature rules featuring equal weights and deterministically chosen evaluation points. The variation of a function and the star discrepancy of a set of points are defined as a prerequisite to the Koksma--Hlawka inequality, which bounds the error of a quasi-Monte Carlo rule by the product of the variation and the star discrepancy. Finally, some evaluation points with small star discrepancy are uncovered, namely the Halton sequence and the Hammersley set.