According to the preface of Graham et al. (1994, p. vi), "[Concrete mathematics] is a blend of CONtinuous and disCRETE mathematics. More concretely, it is the controlled manipulation of mathematical formulas using a collection of techniques for solving problems." As the word "concrete" indicates, concrete mathematics focuses on particular problems, techniques, and algorithms rather than very general mathematical objects as considered by pure mathematics.
Major topics in concrete mathematics include sums, recurrence relations, elementary number theory, binomial coefficients, generating functions, discrete probability, and asymptotic methods. These topics differ notably from those commonly considered to fall under discrete mathematics (Graham et al. 1994, p. vi).
