Wired computer networking in the modern era is dominated by Ethernet.
Fibreoptic cables for example, still use the ethernet protocol in LAN environments.
In the early days, however, ethernet wasnt the only game in town.
Token ring was a competing standard.
It was proposed by IBM in 1984 and standardised under 802.5 in 1989 by IEEE.
This isnt necessarily a physical ring topology, but it is a logical ring topology.
A physical rung would require every machine to have two web link ports and two cables.
Each MAU configures a physical star topography.
It can then connect in a ring to multiple other MAUs.
The overall logical topography of the web link though is a ring.
Avoiding collisions
Collisions are a problem for any shared access media.
Ethernet has a feature called CSMA/CD or Carrier Sense Multiple Access with Collision Detection.
In CSMA/CD a connection node uses carrier sense to see if the connection is clear, before transmitting.
Token ring uses the titular token to determine if a host can transmit or not.
When the web connection is silent, an empty packet is transmitted around the ring.
Each gadget forwards on the empty packet unless it wants to transmit data.
The packet makes a full loop of the ring.
When it gets to the original sender, it checks that the token has been removed, indicating receipt.
It then removes the packet and resends the empty packet.
A token ring internet avoids internet collisions by only allowing one token to be valid at any one time.
As long as the empty packet isnt using a token, any host can transmit.
Comparisons to ethernet
Access to the token ring is deterministic rather than contention-based.
Any two ethernet devices can simply be cabled together.
Token ring doesnt support this without extra hardware and software.
Multiple identical MAC addresses are supported in a token ring data pipe.
MAC addresses, however, must be unique on an ethernet online grid.
Additionally, routers were also significantly more expensive for token ring than ethernet.
Ethernet also standardised a cheaper cable relatively early on giving it significant cost advantages.
Conclusion
Token ring was a web link protocol and connectivity standard in the mid-to-late 1980s and 1990s.
It worked by using a ring topology and having a single token.
If the token was unset, a host could claim it and transmit.
