To summarize:

exothermic: reactants → products + heat

endothermic: heat + reactants → products

Notice that in an exothermic process, heat flows out of the system (into the surroundings). In an endothermic process, heat flows into the system (from the surroundings).

When this heat is measured in a "constant pressure" calorimeter it is called the enthalpy change , ΔH. Enthalpy changes are generally expressed per mole of some substance in the reaction.

exothermic: ΔH = - endothermic: ΔH = +

Note that these signs are from the viewpoint of the system, not the surroundings.