An information group is disclosed for enabling user to retrieve and modify information and interact with other user. An information group is defined by three attributes as location, time span and topic. User has to meet requirement on an information group's location and time span attributes in order to interact with information stored inside information group and communicate with other users inside the same information group. Information group dynamically adjusts its location and life span attributes based on its interaction with user. When multiple information groups are available to a user, they are ranked based on their location attribute and user information and presented to user in the ranked order. Several applications enabled by our invention are disclosed, including but not limited to transportation sharing, connecting users that share a common interests, event signing up, or service or product promotion.