The network model extends the hierarchical by allowing multiple parents and children.
In order to retrieve data from these databases, the whole tree needs to be traversed starting from the root node.
The hierarchical structure is used primarily today for storing geographic information and file systems.
[citation needed] Currently, hierarchical databases are still widely used especially in applications that require very high performance and availability such as banking, health care, and telecommunications.
The organization could store the computer hardware information in a separate table that includes each part's serial number, type, and the employee that uses it.
In contrast to tree structures usually found in computer software algorithms, in this model the children point to the parents.
[citation needed] However, the model is only a special case of a general adjacency list for a graph.