+The @code{nnimap} and @code{gmane} search engines should work with no
+configuration. Other engines require a local index that needs to be
+created and maintained outside of Gnus.
+
+
+@node Basic Usage
+@subsection Basic Usage
+
+In the group buffer typing @kbd{G G} will search the group on the
+current line by calling @code{gnus-group-make-nnir-group}. This prompts
+for a query string, creates an ephemeral @code{nnir} group containing
+the articles that match this query, and takes you to a summary buffer
+showing these articles. Articles may then be read, moved and deleted
+using the usual commands.
+
+The @code{nnir} group made in this way is an @code{ephemeral} group, and
+some changes are not permanent: aside from reading, moving, and
+deleting, you can't act on the original article. But there is an
+alternative: you can @emph{warp} to the original group for the article
+on the current line with @kbd{A W}, aka
+@code{gnus-warp-to-article}. Even better, the function
+@code{gnus-summary-refer-thread}, bound by default in summary buffers to
+@kbd{A T}, will first warp to the original group before it works its
+magic and includes all the articles in the thread. From here you can
+read, move and delete articles, but also copy them, alter article marks,
+whatever. Go nuts.
+
+You say you want to search more than just the group on the current line?
+No problem: just process-mark the groups you want to search. You want
+even more? Calling for an nnir search with the cursor on a topic heading
+will search all the groups under that heading.
+
+Still not enough? OK, in the server buffer
+@code{gnus-group-make-nnir-group} (now bound to @kbd{G}) will search all
+groups from the server on the current line. Too much? Want to ignore
+certain groups when searching, like spam groups? Just customize
+@code{nnir-ignored-newsgroups}.
+
+One more thing: individual search engines may have special search
+features. You can access these special features by giving a prefix-arg
+to @code{gnus-group-make-nnir-group}. If you are searching multiple
+groups with different search engines you will be prompted for the
+special search features for each engine separately.
+
+
+@node Setting up nnir
+@subsection Setting up nnir
+
+To set up nnir you may need to do some prep work. Firstly, you may need
+to configure the search engines you plan to use. Some of them, like
+@code{imap} and @code{gmane}, need no special configuration. Others,
+like @code{namazu} and @code{swish}, require configuration as described
+below. Secondly, you need to associate a search engine with a server or
+a backend.
+
+If you just want to use the @code{imap} engine to search @code{nnimap}
+servers, and the @code{gmane} engine to search @code{gmane} then you
+don't have to do anything. But you might want to read the details of the
+query language anyway.