If you want to perform some command on several groups, and they appear subsequently in the group buffer, you would normally just give a numerical prefix to the command. Most group commands will then do your bidding on those groups.
However, if the groups are not in sequential order, you can still perform a command on several groups. You simply mark the groups first with the process mark and then execute the command.
Toggle the process mark for the current group
nil, set the process mark
for the current group.
Remove the process mark, if any, from the current group
Remove the process mark from all groups (
Mark groups in region (
Mark all groups in the buffer (
Mark all groups that match some regular expression
Also see Process/Prefix.
If you want to execute some command on all groups that have been marked
with the process mark, you can use the M-&
gnus-group-universal-argument) command. It will prompt you for
the command to be executed.