I am studiing economic sciences since 5 years. I'm looking for people interested by the same subject. Here is my dedinition of IER (informal economic relations): when one person transfer some property rights without any formal reception of something in exchange we'll say that he established the IER. In french: Si une personne transfert des droits des propriete a une autre sans une contrepartie determine formellement nous dirons qu'il a etablit des REI.