A page can and should be divided into sections, using the section heading syntax. For each page with more than three section headings, a table of contents (TOC) is automatically generated.
Sections are created by creating their headings, as below.
==Section== ===Subsection=== ====Sub-subsection====
Please do not use only one equals sign on a side (=Heading=). This would cause a section heading to be as large as the page's name (title).
For registered users who use the preference setting Auto-number headings, sections are numbered in the table of contents and at beginning of each section heading.
Headings of sections (including subsections) should be unique on a page. Using the same heading more than once on a page causes problems:
A section of a page can be a transclusion of a separate page or template. See Help:Template#Composite pages. This in effect gives the section its own separate edit history (i.e., the page history of the transcluded page) and also allows registered users to watch it separately.
In a page calling a template with sections, the sections in the template are numbered according to their position in the rendered page, e.g. if the template tag is in the third section, then the first section of the template is numbered four. Any text in the template before its first section shows up as part of the section with the template tag, and any text after the tag before a new heading shows up as part of the last section of the template. This may be done deliberately, but can usually better be avoided (see also below).
In MediaWiki software, a section heading in wikitext is defined by a regular expression, /(^={1,6}.*?={1,6}\s*?$)/m (m refers to multi-line mode).
For each page with more than three headings, a table of contents (TOC) is automatically generated from the section headings, unless:
When either __FORCETOC__ or __TOC__ (with two underscores on either side of the word) is placed in the wikitext, a TOC is added even if the page has fewer than four headings.
With __FORCETOC__, the TOC is placed before the first section heading. With __TOC__, it is placed at the same position where this code is placed. This allows any positioning, e.g. on the right or in a table cell. In old versions of MediaWiki, it also allows multiple occurrence, e.g. in every section (However, this seems only useful if the sections are long, so that the TOCs take up only a small part of the total space.).
There may be some introductory text before the TOC, known as the "lead". Although usually a heading after the TOC is preferable, __TOC__ can be used to avoid being forced to insert a meaningless heading just to position the TOC correctly, i.e., not too low.
Using __NOTOC__ it is possible to disable the normal table of contents. Section links, as explained below, allow creating compact ToCs, e.g. alphabetical [[#A|A]] [[#B|B]] etc.
The TOC's depth can be limited by the use of Template:TOClimit. This template can reduce the number of "header levels" visible to the reader – thus avoiding the problem of an overwhelming TOC when an article has many headings and sub-headings.
This Table of contents can be forced onto a floating table on the right hand of the screen with the code below:
{|
| __TOC__
|}
It is possible to limit the depth of sub-sections to show in the TOC globally using $wgMaxTocLevel. If configuration setting $wgMaxTocLevel in LocalSettings.php is set to 3 for example, only first and second level headings show up in the TOC. Until version 1.10.0rc1, there is a bug in the parser making a limited TOC display incorrectly. A simple solution is proposed in bug report 6204.
In the HTML code for each section there is an anchor HTML element "a" with both "name" and "id" attributes holding the section title. This enables linking directly to sections. These section anchors are automatically used by MediaWiki when it generates a table of contents for the page, and therefore when a section heading in the ToC is clicked, it will jump to the section. Also, the section anchors can be manually linked directly to one section within a page.
The HTML code generated at the beginning of this section, for example, is:
<p><a name="Section_linking" id="Section_linking"></a></p> <h2>Section linking</h2>
A link to this section (Section linking) looks like this:
[[Help:Section#Section_linking|Section linking]]To link to a section in the same page you can use [[#section name|displayed text]], and to link to a section in another page [[page name#section name|displayed text]].
The anchors disregard the depth of the section; a link to a subsection or sub-subsection etc. will be [[#subsection name]] and [[#sub-subsection name]] etc.
An underscore and number are appended to duplicate section names. E.g. for three sections named "Example", the names (for section linking) will be "Example", "Example_2" and "Example_3". However, after editing section "Example_2" or "Example_3" (see below), one, confusingly, arrives at section "Example" from the edit summary.
If a section has a blank space as heading, it results in a link in the TOC that does not work. For a similar effect see NS:0.
To create an anchor target without a section heading, you can use a span: <span id="anchor_name"></span> but this won't work with some very old browsers.
Notes:
For linking to an arbitrary position in a page see Section linking (anchors).
A link that specifies a section of a redirect page corresponds to a link to that section of the target of the redirect.
A redirect to a section of a page may also work in some environments (see bug 218), try e.g. the redirect page Section linking and redirects. (One might have to force reload CSS style sheets.)
A complication is that, unlike renaming a page, renaming a section does not create some kind of redirect. Also, there is no separate backlink feature for sections, pages linking to the section are included in the list of pages linking to the page. Possible workarounds:
Redirect pages can be categorized by adding a category tag after the redirect command. In the case that the target of the redirect is a section, this has to some extent the effect of categorizing the section: through the redirect the category page links to the section; however, unless an explicit link is put, the section does not link to the category. On the category page, redirects are displayed with class redirect-in-category, so they can be shown in e.g. italics; this can be defined in MediaWiki:Common.css. See also WP:Categorizing redirects.
Sections can be separately edited by clicking special edit links labeled "[edit]" by the heading, or by right clicking on the section heading, depending on the preferences set. This is called "section editing feature" (Preferences -> Editing -> "Enable section editing via [edit] links"). Section editing feature will take you to an edit page by a URL such as
http://en.wikipedia.org/w/wiki.phtml?title=Help:Section&action=edit§ion=2
Note that here section numbers are used, not section titles; subsections have a single number, e.g. section 2.1 may be numbered 3, section 3 is then numbered 4, etc. You can also directly type in such URLs in the address bar of your browser.
This is convenient if the edit does not involve other sections and one needs not have the text of other sections at hand during the edit (or if one needs it, open the section edit link in a new window, or during section editing, open the main page in a different window). Section editing alleviates some problems of large pages.
"__NOEDITSECTION__" anywhere on the page will remove the edit links. It will not disable section editing itself; right clicking on the section heading and the url still work.
Inserting a section can be done by editing either the section before or after it, merging with the previous section by deleting the heading. Note that in these cases the preloaded section name in the edit summary is not correct, and has to be changed or deleted.
Adding a section at the end can also be done with a URL like http://meta.wikimedia.org/w/wiki.phtml?title=Meta:Sandbox&action=edit§ion=new . On talk pages and pages with in the wikitext the code __NEWSECTIONLINK__ a special link labeled with the message with id 'addsection' (talk), e.g. "+" or "Post a new comment", is provided for this. In this case, a text box having as title the message with id 'subject' (talk), e.g. "Subject/headline", will appear and the content you type in it will become the section heading. There is no inputbox for the edit summary, it is automatically created according to the pattern of message with id 'newsectionsummary' (talk), where "/* $1 */" represents a right arrow linking to the new section and, with CSS-class "autocomment", the name of the section followed by " - ". In the case of the default of message newsectionsummary this is followed by the text "new section". The user cannot provide more text for the edit summary than just the header itself (use the method mentioned earlier if that is desired).
Parameter "preloadtitle" provides initial content of the "Subject/headline" box, e.g.:
http://meta.wikimedia.org/w/wiki.phtml?title=Meta:Sandbox&action=edit§ion=new&preloadtitle=pqr
It can be edited before saving.
See also linking in an edit summary to a section, "Post a comment" feature, and w:Wikipedia:Village_pump_(technical)#New_section.
In general, no particular link for editing the introductory text before the first section heading is provided. However, section editing feature can also be applied to this part by giving 0 as the section number such as http://en.wikipedia.org/w/wiki.phtml?title=Help:Section&action=edit§ion=0 . A less cumbersome way to obtain this link is to use any section edit link of the page, and change the number of the section to zero.
Javascript can also create this URL, see w:Wikipedia:WikiProject User scripts/Scripts/Edit Top.
The {{Edit-first-section}} and {{Edit-top-section}} templates create an edit link for the section 0. Each is positioned slightly differently. Copy these templates to your wiki. (Note: These are not available on the English Wikipedia due to the availability of "Special:Preferences > Gadgets > User Interface Gadgets".)
See also Help:Section editing demo.
The preview in section editing does not always show the same as the corresponding part of the full page, e.g. if on the full page an image in the previous section intrudes into the section concerned.
The edit page shows the list of templates used on the whole page, i.e. also the templates used in other sections.
Subsections are included in the part of the section that is edited. Section numbering is relative to the part that is edited, so on the relative top level there is always just number 1, relative subsections all have numbers starting with 1: 1.1., 1.2, etc.; e.g., when editing subsection 3.2, sub-subsection 3.2.4 is numbered 1.4. However, the heading format is according to the absolute level.
If a page has very large sections, or is very large and has no division into sections, and one's browser or connection does not allow editing of such a large section, then one can still: