A computer-implemented process for groups includes forming a group using a series of invitation, acceptance and confirmation handshake messages. A location center for the group is calculated as an average location for all members of the group as calculated by the computer from data included in at least one message of the messages. The computer calculates a perimeter for the group from the data. The computer calculates a time decay parameter for the group from the data. The computer calculates a group profile for the group based on at least the location center, the perimeter and the time decay parameter. The computer adds a new member to the group, by any member triggering an invitation process with the new member. The computer recalculates the group profile on acceptance by the new member and transmits the recalculated group profile to all members including a confirmation message to the new member.