What type of reaction occurs when an acid and a base react to form water and a salt?

When an acid and a base react to form water and a salt, the process is classified as a neutralization reaction. This type of reaction involves the combination of hydrogen ions (from the acid) and hydroxide ions (from the base) to produce water. The remaining ions then combine to form a salt.

Neutralization reactions are key in chemistry because they often help to illustrate the concept of pH and the balancing of acidity and basicity. It is important to recognize that this reaction results in the establishment of a more neutral pH level compared to the starting materials, exemplifying the fundamental interaction between acids and bases.

The other listed reactions do not involve this specific combination of an acid and a base leading to the formation of water and salt. Redox reactions involve the transfer of electrons and changes in oxidation states, decomposition reactions break down a compound into simpler substances, and combustion reactions typically involve a substance reacting with oxygen to produce heat and light, often forming carbon dioxide and water.