Two documents look identical on screen. One has headings made with the Heading 1 style; the other has bold 16pt text. Export both to PDF and one has a navigation tree and the other does not. Convert both to HTML and one produces real heading elements and the other produces paragraphs. Ask Word to build a table of contents and one works.
The difference is invisible on the page and decides everything that happens to the document afterwards.
Direct formatting versus styles
Direct formatting applies appearance to the characters you selected. Bold, 16pt, dark blue. That is all the file records.
A style is a named definition applied to a paragraph. The paragraph is a Heading 1; Heading 1 currently means 16pt bold dark blue, and that definition lives in one place.
The practical difference is that a style carries meaning and direct formatting carries only appearance. Everything downstream reads meaning:
| Feature | Needs styles |
|---|---|
| Table of contents | Yes |
| Navigation pane | Yes |
| Restyling the whole document | Yes |
| Tagged, accessible PDF export | Yes |
| Clean conversion to HTML or Markdown | Yes |
| Looking right on screen | No |
That last row is why the habit persists. Formatting by hand looks correct immediately, and the cost arrives later, usually when somebody asks for the document in another format.
What it costs at conversion time
This is where the abstract argument becomes concrete. A document formatted with real styles run through DOCX to HTML produces <h1>, <h2>, <ul> and <table> elements: structure a browser and a screen reader both understand.
The same document formatted by hand produces a flat sequence of paragraphs carrying inline styling, because there was no structure to map. You get the appearance approximately and the structure not at all, and someone has to rebuild the headings manually.
DOCX to Markdown has the same dependency, for the same reason: ## is a heading level, and a heading level is what the style provided.
Lists and spacing, the two other classics
Manual bullets. Typing a hyphen and a space produces something that looks like a list and is a paragraph beginning with a hyphen. It will not renumber, will not indent consistently, and converts to nothing.
Empty paragraphs for spacing. Pressing Enter twice is the most common way documents acquire inconsistent gaps, because the space then depends on the font size of an invisible paragraph. Space Before and Space After in the style definition is the mechanism that exists for this, and it stays consistent when the document is restyled.
Style bloat, and the fastest way out
Pasting content from another document brings that document's style definitions with it. Do it repeatedly and the style list fills with Heading 1, Heading 11, Heading 1 + Calibri, all subtly different, and the document acquires several fonts nobody chose.
Repairing this by editing each style is slow and rarely converges. The faster route is to remove everything and start from a known state:
- Strip all formatting to reduce the document to plain text with paragraph breaks.
- Apply your template.
- Apply Heading 1, Heading 2 and list styles where they belong.
That sounds drastic and is usually quicker than the alternative, because you end with a document that has exactly the styles you intended rather than one you have negotiated with.
A template worth having
A template is a document containing style definitions and no content. Setting one up once takes about twenty minutes and pays for itself the first time somebody asks for a different font throughout.
Define Heading 1 to 3, Body Text, a list style and a caption style. Set fonts, sizes, colours and spacing in the definitions rather than on the text. Then every new document starts correct, and changing the look of all of them later is a change in one place.
The test for whether it worked: open the navigation pane. If your headings are listed there, the document has structure. If it is empty, the document has appearance only, and every conversion from here will be a rebuild.