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### 4.1 Hiding Headers

The top section of each article is the head. (The rest is the body, but you may have guessed that already.)

There is a lot of useful information in the head: the name of the person who wrote the article, the date it was written and the subject of the article. That's well and nice, but there's also lots of information most people do not want to see—what systems the article has passed through before reaching you, the `Message-ID`, the `References`, etc. ad nauseam—and you'll probably want to get rid of some of those lines. If you want to keep all those lines in the article buffer, you can set `gnus-show-all-headers` to `t`.

Gnus provides you with two variables for sifting headers:

`gnus-visible-headers`
  If this variable is non-`nil`, it should be a regular expression that says what headers you wish to keep in the article buffer. All headers that do not match this variable will be hidden.

  For instance, if you only want to see the name of the person who wrote the article and the subject, you'd say:

                (setq gnus-visible-headers "^From:\\|^Subject:")

  This variable can also be a list of regexps to match headers to remain visible.

`gnus-ignored-headers`
  This variable is the reverse of `gnus-visible-headers`. If this variable is set (and `gnus-visible-headers` is `nil`), it should be a regular expression that matches all lines that you want to hide. All lines that do not match this variable will remain visible.

  For instance, if you just want to get rid of the `References` line and the `Xref` line, you might say:

                (setq gnus-ignored-headers "^References:\\|^Xref:")

  This variable can also be a list of regexps to match headers to be removed.

  Note that if `gnus-visible-headers` is non-`nil`, this variable will have no effect.

Gnus can also sort the headers for you. (It does this by default.) You can control the sorting by setting the `gnus-sorted-header-list` variable. It is a list of regular expressions that says in what order the headers are to be displayed.

For instance, if you want the name of the author of the article first, and then the subject, you might say something like:

         (setq gnus-sorted-header-list '("^From:" "^Subject:"))

Any headers that are to remain visible, but are not listed in this variable, will be displayed in random order after all the headers listed in this variable.

You can hide further boring headers by setting `gnus-treat-hide-boring-headers` to `head`. What this function does depends on the `gnus-boring-article-headers` variable. It's a list, but this list doesn't actually contain header names. Instead it lists various boring conditions that Gnus can check and remove from sight.

These conditions are:

`empty`
  Remove all empty headers.
`followup-to`
  Remove the `Followup-To` header if it is identical to the `Newsgroups` header.
`reply-to`
  Remove the `Reply-To` header if it lists the same addresses as the `From` header, or if the `broken-reply-to` group parameter is set.
`newsgroups`
  Remove the `Newsgroups` header if it only contains the current group name.
`to-address`
  Remove the `To` header if it only contains the address identical to the current group's `to-address` parameter.
`to-list`
  Remove the `To` header if it only contains the address identical to the current group's `to-list` parameter.
`cc-list`
  Remove the `Cc` header if it only contains the address identical to the current group's `to-list` parameter.
`date`
  Remove the `Date` header if the article is less than three days old.
`long-to`
  Remove the `To` and/or `Cc` header if it is very long.
`many-to`
  Remove all `To` and/or `Cc` headers if there are more than one.

To include these three elements, you could say something like:

         (setq gnus-boring-article-headers
               '(empty followup-to reply-to))

This is also the default value for this variable.