BGP peer groups
Peer groups are used to simplify BGP configuration especially when there is a large number of BGP peers. Neighbors are added to peer groups, and then BGP configurations can be applied to all neighbors by simply applying them once to the peer group.
This simplifies configuration, as well as CPU processing power, since the same update is created once and shared with multiple neighbors.
Peer groups should not be confused with BGP peer templates. A BGP neighbor cannot be configured to work with both peer groups and peer templates.
On the Cisco IOS-XR, one can use the BGP neighbor-group command to achieve similar results.