Recent progress in flavour-changing-neutral-current (FCNC) processes is reviewed with particular emphasis on the role of QCD. Standard model (SM) is consistent with data. In particular, the rate and final-state distributions in radiative rare B decays, B → X s + γ , are well accounted for in the SM in terms of the short-distance contribution. The CLEO measurement of the inclusive rate B ( B → X s γ ) = (2.32 ± 0.67) × 10 −4 yields | V ts |/| V cb | = 0.85 ± 0.23, in agreement with unity expected from the unitarity of the CKM matrix. Likewise, most QCD-based theoretical estimates, using short-distance dominance, yield for the exclusive-to-inclusive decay rate ratio B ( B → K * + γ )/ B ( B → X s + γ ) = 0.1 - 0.2, in agreement with the data giving 0.19 ± 0.1 for the same quantity. Along the same lines, the present measurements of the branching ratio B ( B → K * + γ ) and upper limits on the branching ratios B ( B → ρ + γ ) and B ( B → ω + γ ) can be interpreted in terms of an upper limit on the CKM matrix element ratio, yielding | V td |/| V ts | ≤ 0.75. This bound is less restrictive than the unitarity bounds and the ones that follow from the lower limit on the B 0 - B¯ 0 mixing ratio Δ M s /Δ M d > 11.3, reported recently by the ALEPH collaboration. The potential of rare B decays in searching for physics beyond the standard model is also reviewed with emphasis on the decays B → X s + γ and B → X s l + l − .