Need more detailed info on etcd component...

Hi
It would be very help to have a flow digram that show how a request from a client to an etcd...
I, for one, are not able to visualize what the flow looks like based on this paragraph:
"Do clients have to send requests to the etcd leader?
[Raft](https://raft.github.io/raft.pdf) is leader-based; the leader handles all client requests which need cluster consensus. However, the client does not need to know which node is the leader. Any request that requires consensus sent to a follower is automatically forwarded to the leader. Requests that do not require consensus (e.g., serialized reads) can be processed by any cluster member."
So, based on the header fo this paragraph, it suggests that there are more than one instance of etcd in a cluster....there's a "ectd leader" and "ectd followers/workers"? If so, how the leader works when it gets an API request? etc...
Thanks
J.N