A featured snippet is that box that shows up at the very top of some Google searches, even before the first organic result, with an excerpt from a page that directly answers the question. It's called "position zero" because it technically sits before position one, and it captures a huge share of clicks: when someone sees their question answered right there, they often don't click through to any result at all, but when they do click, it's usually on the site occupying that box.
What's interesting, and what makes it worth chasing, is that Google doesn't necessarily pick the featured snippet from among the pages holding the top spot. It can pick a page ranking fourth or fifth if its content format answers the specific question better. That opens a real opportunity for sites that don't yet dominate the top positions.
The three formats Google tends to feature
The paragraph one, which answers a direct question in two or three clear sentences right after the heading that poses it. The list one, which works very well for "steps to do X" or "types of Y" content, as long as it's structured as an actual HTML list, not as running text. And the table one, ideal for comparing prices, features, or any data that lends itself to rows and columns.
How to structure content to have a shot at it
Start by identifying real questions people search around your topic (keyword tools, Google's "people also ask" section, or simply the questions your own customers ask you) and use them as H2 or H3 headings pretty much as-is, without over-paraphrasing. Right below each question, put the most direct possible answer in the first lines, and then, if you want, expand with more detail: Google tends to pull those first sentences, so that's where the concrete answer needs to live, not buried at the end of the paragraph.
Why "ranking at the top" doesn't always mean more traffic
There's an important nuance here: if your snippet answers the question so completely that nobody needs to click through to learn more, you can gain brand visibility without gaining actual traffic. The trick is to answer enough to deserve the feature, while making it clear there's more value in visiting the full page (examples, specific cases, the logical next step), instead of using up the entire answer in those two sentences.
Frequently asked questions
Do I need to be in Google's top 3 to land a featured snippet?
It's not required, though it helps: most featured snippets come from pages already on page one of results, usually somewhere between positions one and five.
Can I choose which excerpt from my page gets featured?
Not directly: Google automatically decides which excerpt to use based on how the content is structured. What you can do is make its job easier by structuring the answer clearly right after the question.
Do featured snippets affect voice search SEO?
Yes, quite a bit: voice assistants (like Google Assistant) often read out loud exactly the featured snippet content when answering a spoken question, so optimising for snippets also indirectly optimises for voice search.