A bi-lateral agreement made by network operators to guarantee access to each others customers at no cost to either party
An agreement devised between two network service providers for the purpose of private and direct data exchange between their respective networks. Peering agreements usually result in faster and more efficient data exchange.
A business relationship whereby ISPs provide to each other connectivity to each other's downstream transit customers. The terms peering and peer are often, particularly in the US, used to refer to the relationship with downstream transit customers and upstream transit providers.