Why does heading order matter?
Headings are the outline of your page, and an outline only works if the levels nest. Skipping from a top-level heading straight to a third-level one tells anything reading structurally that a section is missing, when really it was a styling decision.
What it actually is
If you stripped every word from a well-structured page and kept only the headings, you should be left with something that reads like a table of contents. That is precisely what crawlers, screen readers and answer engines extract. The visual size of a heading is a design choice; the level is a statement about what belongs inside what.
Why it matters
Answer engines increasingly quote sections rather than pages, and the heading structure is how they decide where a section begins and ends. A clean outline means a passage can be lifted with its context intact and attributed to you. A broken one means your content is harder to excerpt, so it gets excerpted less — you are not penalised, you are simply passed over for something easier to use.
What good looks like
A single top-level heading, then subheadings that descend one level at a time, with no gaps. Each heading genuinely introduces the content beneath it rather than decorating it, and a reader skimming only the headings would come away with an accurate summary of the page.
Being honest about it
On a short page with a handful of sections this barely matters and we will say so. It becomes genuinely important on long-form content, documentation and anything you hope will be quoted — which is exactly the content most worth investing in. It also happens to be one of the few technical signals with a direct, non-hypothetical accessibility benefit, which is worth something on its own.
Where most sites go wrong
The most common failure is styling by level: a designer needs smaller text, reaches for a lower heading, and the outline acquires a hole. It is invisible on the rendered page and obvious to anything reading the structure. The second is the heading used for emphasis mid-paragraph, which inserts a phantom section break into the outline and splits a coherent passage into two incoherent ones.