Use the == style markup for headlines, not '''. Start with "==" (that's two equal signs). Note that with the == brackets used, no space under the headline is needed. The space should be removed.
Major benefits of marking headers this way:
- sections can be automatically numbered for users with that preference set,
- a table of contents can be generated from the sections,
- sections can be edited individually (see Wikipedia:Section),
- words within properly marked headers are given greater weight in searches.
- Headlines also help readers by breaking up the text and outlining the article.
- Visually-impaired users may be using software which begins by giving a summary of the article, built from the heading tags. [1]
Capitalize the first word and any proper nouns in headlines, but leave the rest lower case.
Avoid links within headers. Depending on settings, some users may not see them clearly. Much better to put the appropriate link in the first sentence under the header.
Nesting
Nest headings correctly, for the same reasons as above. The top-level heading of any page is a H1 which gives the article title. The headings within the article must therefore be H2, ie "==".
Below that, the "child" heading of "==" is "===", the child of that is "====" and so on.
The MoS says "Avoid links within headers. Depending on settings, some users may not see them clearly. It is much better to put the appropriate link in the first sentence under the header."