Clear hierarchy: The network extends downward from the root node (such as the main switch) into multiple branches, each of which can be further subdivided, forming a hierarchical structure similar to a family tree.
Unidirectional connection: Data usually flows in the "parent node → child node" direction, but some protocols support bidirectional communication.
No loops: There is only a unique path between any two nodes, preventing broadcast storms caused by data loops.

Root node: Located at the highest level, it is the core of the entire network, responsible for managing and controlling data transmission across the network.
Branch node: Multi-level child nodes extending downward from the root node, capable of connecting other child nodes, serving as data relay and network expansion.
Terminal node: Located at the bottom of the network, not connecting any other child nodes, it is the final recipient or sender of data.
Connection link: The physical or logical connection channels between nodes.
Network protocols and control mechanisms: Software or algorithms that define communication rules between nodes.

1. Upward transmission (Terminal node → Root node): Terminal devices send data to directly connected intermediate nodes, which receive the data and decide whether to continue forwarding based on the destination address. Data is transmitted step by step upwards until it reaches the root node or the branch where the target node is located.
2. Downward transmission (Root node → Terminal node): The root node or intermediate nodes send data to the next level node, with data transmitted downward along the branches until it reaches the target terminal device.
3. Broadcasting and multicasting: The root node can broadcast data to all branches, with intermediate nodes responsible for forwarding data to all child nodes; multicast transmission targets only specific branches or node groups.

Easy to expand: Many branches and sub-branches can be extended, making it easy to add new branches or nodes to the network.
Flexible layout: Highly collapsible, very suitable for constructing network backbones, and can effectively protect wiring investments.
Cost control: By adopting a reasonable connection scheme, the total cost of communication lines can be lower than that of a star structure.
Poor resource-sharing capability: Information has only a single routing channel, which is not conducive to resource sharing between nodes.
Lower reliability: Any link failure can affect the normal operation of the entire or part of the network.

Tree topology is a hierarchical structure with root and branch nodes, a hybrid of star and bus topologies, with significant advantages in network scalability. If the root node fails, the entire network cannot function normally, but it has strong local fault isolation capabilities, and the total cost of communication lines is generally lower than that of a star structure.
In star topology, all communications are controlled by a central node, with all nodes connected to a central point called a hub. Expansion is limited by the number of ports on the central hub. If the central node fails, it may cause a complete network shutdown, but terminal node failures do not affect other nodes, and the implementation cost of star topology is higher.