Word offers a set of built in “styles” that can be used to apply formatting to heading text. There are a number of advantages to using styles:

• headings will be formatted consistently
• formatting can be changed easily by modifying the styles rather than each line/paragraph
• headings can be used to generate a table of contents
• headings can be automatically numbered
• blind users working with screen readers can easily navigate between headings
• when saving as PDF headings can be used to create bookmarks in the PDF document

References

Make your Word documents accessible

Make your PowerPoint presentations accessible