In chemistry, homogeneous catalysis is catalysis in a solution by a soluble catalyst. Strictly speaking, homogeneous catalysis refers to catalytic reactions where the catalyst is in the same phase as the reactants. Homogeneous catalysis applies to reactions in the gas phase and even in solids.

In chemistry, heterogeneous catalysis refers to the form of catalysis where the phase of the catalyst differs from that of the reactants. Phase here refers not only to solid, liquid, vs gas, but also immiscible liquids, e.g. oil and water

An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used in pesticides.

Catalyst poisoning refers to the partial or total deactivation of a catalyst. Poisoning is caused by chemical compounds. Although usually undesirable, poisoning may be helpful when it results in improved selectivity. For example, Lindlar's catalyst is poisoned so that it selectively catalyzes the reduction of alkynes.

In genetics, a promoter is a region of DNA that initiates transcription of a particular gene. Promoters are located near the transcription start sites of genes, on the same strand and upstream on the DNA. Promoters can be about 100–1000 base pairs long