A theorem due to Scarf in 1967 is examined in detail. Several versions ofthis theorem exist, some which appear at first unrelated.Two versionscan be shown to be equivalent to a result due to Sperner in 1928: fora proper labelling of the vertices in a simplicial subdivision of an n-simplex,there exists at least one elementary simplex which carries all labels {0,1,..., n}.A third version is more akin to Dantzig;;s simplex method and is also examined.In recent years many new applications in combinatorics have been found,and we present several of them. Two applications are in the area of fair division: cake cuttingand rent partitioning. Two others are graph theoretic: showing the existenceof a fractional stable matching in a hypergraph and the existence of a fractional kernel in adirected graph. For these last two, we also show the second implies the first.