A good search bar is visible without a click, wide enough to read a full query, suggestive from the second character, forgiving of typos and phrasing, fast enough to feel instant, and never returns a dead end. Visibility and zero-result behaviour matter more than ranking sophistication.
The rules, in priority order
Always visible — an open field in the header, not an icon that expands into one.
Wide enough that a full query stays readable while typing.
A placeholder that shows a real example query rather than the word "Search".
Suggestions from the second or third character, matching mid-word.
Sub-200ms perceived response; instant beats accurate at this stage.
Filters visible and reversible after results appear.
Empty results that offer corrections, near matches and a route to a human.
Keyboard support — arrow keys, enter, escape, and a shortcut on desktop.
The two mistakes that dominate
Hiding search behind an icon suppresses usage of the highest-intent tool on the page, and the loss never appears in a report because the searches simply never happen.
Treating a zero-result page as an end state is the second. It is the one screen where the site has the visitor's exact words and does nothing with them.
Frequently asked
Where should the search bar go?
The header, on every page, visible without interaction. On mobile, near the top of the viewport rather than inside a collapsed menu.