Over the years, with the advancement of technology and the expansion of populations, man was forced to develop mechanisms to keep certain issues under control.
Part of these mechanisms involves kashrut supervision. In the past, when people lived most of their lives in one place, everyone knew each other. Everyone knew the butcher, everyone knew the baker, and they trusted each other's kashrut standards. Therefore, it wasn't necessary for these people to have a certificate of supervision.
As time passed and mass food production began, this knowledge and trust became less clear, so people found it necessary to create teams of specialized rabbis to review and certify that the food produced complies with kashrut standards.
Today, there are hundreds of such teams around the world, with different names and schools, that is, with different standards and customs regarding what is kosher and what is not.
Therefore, when it comes to buying a particular food, one should look for the seal of rabbinic supervision or know the "list" of foods that this supervision approves.
Examples of surnames of rabbis who carry out this task in Argentina are: Feigelstock, Openheimer, Ekstein, Sofer, Chehebar and Yabra.