Most of the keystrokes in the summary buffer can also be used in the article buffer. They should behave as if you typed them in the summary buffer, which means that you don't actually have to have a summary buffer displayed while reading. You can do it all from the article buffer.
The key v is reserved for users. You can bind it to some command or better use it as a prefix key.
A few additional keystrokes are available:
gnus-article-next-page). This is exactly the same as h <SPC> h.
gnus-article-prev-page). This is exactly the same as h <DEL> h.
Message-IDand you press C-c ^, Gnus will try to get that article from the server (
gnus-article-mail). If given a prefix, include the mail.
gnus-article-next-button). This only makes sense if you have buttonizing turned on.
gnus-article-reply-with-original). If the region is active, only yank the text in the region.
gnus-article-wide-reply-with-original). If the region is active, only yank the text in the region.
gnus-article-followup-with-original). If the region is active, only yank the text in the region.