What is an exothermic reaction give examples

Examples:

• Combustion (burning) of fuels like wood, natural gas, or propane. For instance, the burning of methane: $\text{CH}_{4}(g) + 2\text{O}_{2}(g) \to \text{CO}_{2}(g) + 2\text{H}_{2}\text{O}(l) + \text{energy}$.
• The neutralization reaction between an acid and a base, such as hydrochloric acid and sodium hydroxide: $\text{HCl}(aq) + \text{NaOH}(aq) \to \text{NaCl}(aq) + \text{H}_{2}\text{O}(l) + \text{heat}$.
• The setting of concrete (hydration of cement).