Extinguishing agents are those substances that, thanks to their physical or chemical properties, are used to put out fire (generally in fires).[1]​.

From the triangle or tetrahedron of fire, the way in which extinguishing agents act can be explained, which is in four ways, each of the faces of the tetrahedron, or as a combination of them:

The most common agents are:

The use of each of them depends on the type of fire of the materials susceptible to catching fire and, in many cases, that the agent does not damage the objects not reached by the fire (as would happen with books in a library if water were used).

https://www.comprarextintoresbaratos.es/normativa-mantenimiento-de-extintores-23.

https://www.extintormadrid.com/agentes-extintores.