Traditionally, a server is a machine or a piece of software that one connects to, and then requests information from. Gnus does not connect directly to any real servers, but does all transactions through one back end or other. But that's just putting one layer more between the actual media and Gnus, so we might just as well say that each back end represents a virtual server.
For instance, the
nntp back end may be used to connect to several
different actual NNTP servers, or, perhaps, to many different ports
on the same actual NNTP server. You tell Gnus which back end to
use, and what parameters to set by specifying a select method.
These select method specifications can sometimes become quite complicated—say, for instance, that you want to read from the NNTP server ‘news.funet.fi’ on port number 13, which hangs if queried for NOV headers and has a buggy select. Ahem. Anyway, if you had to specify that for each group that used this server, that would be too much work, so Gnus offers a way of naming select methods, which is what you do in the server buffer.
To enter the server buffer, use the ^
gnus-group-enter-server-mode) command in the group buffer.
gnus-server-mode-hook is run when creating the server buffer.