+If you wish to implement a system to cross-correlate information, an
+excellent way is to assign @i{tags} to headline. Org-mode has
+extensive support for using tags.
+
+Every headline can contain a list of tags, at the end of the headline.
+Tags are normal words containing letters, numbers, @samp{_}, and
+@samp{@@}. Tags must be preceded and followed by a single colon; like
+@samp{:WORK:}. Several tags can be specified like @samp{:WORK:URGENT:}.
+
+@menu
+* Tag inheritance:: Tags use the tree structure of the outline
+* Setting tags:: How to assign tags to a headline
+* Tag searches:: Searching for combinations of tags
+@end menu
+
+@node Tag inheritance, Setting tags, Tags, Tags
+@section Tag inheritance
+@cindex inheritance, of tags
+
+@i{Tags} make use of the hierarchical structure of outline trees. If a
+heading has a certain tag, all subheadings will inherit the tag as
+well. For example, in the list
+
+@example
+* Meeting with the French group :WORK:
+** Summary by Frank :BOSS:NOTES:
+*** TODO Prepare slides for him :ACTION:
+@end example
+
+@noindent
+the final heading will have the tags @samp{:WORK:}, @samp{:BOSS:},
+@samp{:NOTES:}, and @samp{:ACTION:}. When executing tag searches and
+Org-mode finds that a certain headline matches the search criterion, it
+will not check any sublevel headline, assuming that these likely also
+match, and that the list of matches can become very long. However, this
+may not be what you want, and you can influence inheritance and
+searching using the variables @code{org-use-tag-inheritance} and
+@code{org-tags-match-list-sublevels}.
+
+@node Setting tags, Tag searches, Tag inheritance, Tags
+@section Setting tags
+@cindex setting tags
+
+@kindex M-@key{TAB}
+As Org-mode deals with plain text files, tags can simply be typed into
+the buffer. After a colon, @kbd{M-@key{TAB}} offers completion on all
+tags being used in the current buffer. There is also a special command
+for inserting tags:
+
+@table @kbd
+@kindex C-c C-c
+@item C-c C-c
+@cindex completion, of tags
+Enter new tags for the current headline. The minibuffer will prompt for
+a list of tags and offer completion with respect to all other tags used
+in the current buffer. Several tags, separated by colons, may be
+specified at the prompt. After pressing @key{RET}, the tags will be
+inserted and aligned to @code{org-tags-column}. When called with a
+@kbd{C-u} prefix, all tags in the current buffer will be aligned to that
+column, just to make things look nice. TAGS are automatically realigned
+after promotion, demotion, and TODO state changes (@pxref{TODO basics}).
+@end table
+
+@node Tag searches, , Setting tags, Tags
+@section Tag searches
+@cindex tag searches
+
+Once a tags system has been set up, it can be used to collect related
+information into special lists.
+
+@table @kbd
+@kindex C-c \
+@item C-c \
+Create a sparse tree with all headlines matching a tags search.
+@kindex C-c a m
+@item C-c a m
+Create a global list of tag matches from all agenda files.
+@xref{Matching headline tags}.
+@kindex C-c a M
+@item C-c a M
+Create a global list of tag matches from all agenda files, but check
+only TODO items and force checking subitems (see variable
+@code{org-tags-match-list-sublevels}).
+@end table
+
+A @i{tags} search string can use Boolean operators @samp{&} for AND and
+@samp{|} for OR. @samp{&} binds more strongly than @samp{|}.
+Parenthesis are currently not implemented. A tag may also be preceded
+by @samp{-}, to select against it, and @samp{+} is syntactic sugar for
+positive selection. The AND operator @samp{&} is optional when @samp{+}
+or @samp{-} is present. For example, @samp{+WORK-BOSS} would select all
+headlines that are tagged @samp{:WORK:}, but discard those also tagged
+@samp{:BOSS:}. The search string @samp{WORK|LAPTOP} selects all lines
+tagged @samp{:WORK:} or @samp{:LAPTOP:}. The string
+@samp{WORK|LAPTOP&NIGHT} requires that the @samp{:LAPTOP:} lines are
+also tagged @samp{NIGHT}.
+
+@node Agenda Views, Exporting, Tags, Top
+@chapter Agenda Views
+@cindex agenda views
+
+Due to the way Org-mode works, TODO items, time-stamped items, and
+tagged headlines can be scattered throughout a file or even a number of
+files. To get an overview over open action items, or over events that
+are important for a particular date, this information must be collected,
+sorted and displayed in an organized way.
+
+Org-mode can select items based on various criteria, and display them
+in a separate buffer. Three different views are provided: