Founded by Urie Bronfrenner, this thory focuses on an environmental system that is divided into 5 systems that are influential to an individuals environment. These systems are the individual, microsystem, mesosystem, exosystem and the macrosystem. At the individual level, a person's genetics, physiology, etc are at the level of individual concern. The next system up is the microsystem. This system consists of those people and places that we encounter face-to-face every day. The next system up is the mesosystem which links people from the micro to the exo systems. The next system is the exosystem which consists of those people or places that you encounter weekly or every so often. Examples include your family, friends, doctor, etc. Lastly the final system is the macrosystem. This system consists of the media, policy, social norms, etc that influence our thoughts and actions. Overall, at every level a person is affected by their environment in some way shape or form and each of these systems plays a part in an individual's life. Additionally, the ecological theory follows the life span theory model, but at the same time does not follow the stage theory model.