Let C be a clutter and let I(C) ⊂ R be its edge ideal. This is a survey paper on the algebraic and combinatorial properties of R/I(C) and C, respectively. We give a criterion to estimate the regularity of R/I(C) and apply this criterion to give new proofs of some formulas for the regularity. If R/I(C) is sequentially Cohen-Macaulay, we present a formula for the regularity of the ideal of vertex covers of C and give a formula for the projective dimension of R/I(C). We also examine the associated primes of powers of edge ideals, and show that for a graph with a leaf, these sets form an ascending chain.We are interested in determining which families of clutters have the property that ∆ C is pure, Cohen-Macaulay, or shellable. These properties have been extensively studied, see [10,89,92,93,94,100,102,110,111] and the references there.The above definition of shellable is due to Björner and Wachs [6] and is usually referred to as nonpure shellable, although here we will drop the adjective "nonpure". Originally, the definition of shellable also required that the simplicial complex be pure, that is, all facets have the same dimension. We will say ∆ is pure shellable if it also satisfies this hypothesis. These properties are related to other important properties [10,102,110]:If a shellable complex is not pure, an implication similar to that above holds when Cohen-Macaulay is replaced by sequentially Cohen-Macaulay. Definition 2.2. Let R = K[x 1 , . . . , x n ]. A graded R-module M is called sequentially Cohen-Macaulay (over K) if there exists a finite filtration of graded R-modules (0) = M 0 ⊂ M 1 ⊂ · · · ⊂ M r = M