What Is a Favicon?

The favicon is the small icon representing a site: in the browser tab, in bookmarks, beside the result's title and, for years now, beside the result on mobile too. It is the smallest brand mark a site has and the one seen most often.

Technically it is an image declared with a link element in the document head. Google accepts several values for the rel attribute and several formats; what it requires is that the image be square and its address stay stable.

The minimum size is eight pixels per side, though the documentation itself recommends more than forty-eight so it looks good on various surfaces. The difference between those two figures is not a detail: one is the technical minimum, the other the practical advice.

The name comes from "favorites icon" and from a time when it served only a browser's bookmark list. Today it appears in the tab, in history, on a phone's home screen when somebody saves the site as a shortcut, and beside the search result. The use grew; the file stayed the same.

It deserves distinguishing from Open Graph, which governs the sharing preview, and from other icons declared similarly that are not the same thing: the one a phone uses when adding the site to the home screen is usually larger and declared separately. Confusing the two leaves one of them undefined — and the missing one is always the one in the place you do not check.

Here is what hardly anyone knows and what explains many arguments: Google's documentation states that only one favicon per site is supported, and that a site is defined by the hostname.

Everything else follows from that. Two different subdomains, each with its own address resolution, may carry different icons, because they are two hostnames. A subdirectory of the same host cannot: it inherits the site's and there is no way to give it another.

The practical consequence shows when planning structure. If a brand wants its shop to appear with its own identity in results, domain and subdomain are not interchangeable with a subdirectory — and that decision is made long before anyone thinks about the icon.

One in-between case regularly surprises people: sites with the main presence on one subdomain and the shop on another share the brand but not the icon — and that can be deliberate or accidental. If deliberate, both icons should read as coming from the same house; if accidental, one of the two is usually undeclared and the generic placeholder appears.

And a consequence for international SEO: if country versions live on subdomains, each may carry its own. Them being different rarely makes sense; checking that none was left undeclared when the structure was built certainly does.

It is declared in the head of the home page, alongside the other meta tags. Not on every page: Google reads the favicon information on the host's home page, so an icon declared only on an inner page reaches nowhere.

The file, by contrast, may live wherever you like. The documentation explicitly notes that the address need not be hosted on your own site and gives a CDN as its example, with a relative or absolute path.

What it must not be is blocked. If robots.txt prevents access to the icon's path, the crawler cannot fetch it, and the result is indistinguishable from never having declared it.

One implementation detail saves surprises: if several icon link elements sit in the same head — inherited from different templates, from a plugin and from the theme — it is unclear which wins. The sensible move is to leave one and delete the rest, as with any duplicated meta tag.

And a one-minute check: request the home page the way a crawler would and look for the link element in the delivered HTML, not in the browser inspector. If the head is assembled by code, it can look perfect on screen and be absent from the response — the same problem affecting any declaration in JavaScript.

A change does not show the next day, as with any indexing signal. Google has to recrawl the home page and process the information, and its documentation puts that at anywhere from several days to several weeks, depending on how often its systems decide to refresh the page.

You can request indexing of the home page with URL inspection in Search Console to speed it up, but requesting is not receiving: it still depends on the crawler.

And there is an explicit caveat worth repeating to whoever commissions the work: meeting every guideline does not guarantee the icon appears. Google also excludes what it deems inappropriate, and there is no appeal against that.

It also deserves treating as what it is in results: a brand decision with measurable consequences. In a list of results on mobile, the icon is the first thing distinguishing one entry from the next before anyone reads the title, and that affects CTR without changing a single position.

And a note on contrast: the icon appears on a light or dark ground depending on the device setting. A black symbol on transparency disappears in dark mode, and no tool catches that case; you look at it on a phone in both settings, as with any detail of user experience.

The first is changing the file's address at every redesign. The documentation explicitly asks for a stable URL; every change restarts the waiting period, and meanwhile the old icon may keep appearing in results.

The second is an over-detailed icon. What appears in results is tiny, so a full logo with a wordmark turns into a smudge in the SERP; a simple symbol or a single letter with enough contrast works better.

And the third is declaring it in the article template but not on the home page — which usually happens only once somebody edits the CMS templates by hand. A silent fault: in the browser it looks perfect on every page, including on mobile — and the one page Google looks at for this is the one without it.

A fourth mistake, typical of migrations: changing host and assuming the icon travels. It does not. Moving from one subdomain to another, or one domain to the next, the new host starts with no known favicon, and until Google processes its home page the placeholder appears — with the redirect working perfectly.

And the last: declaring it and never checking again. A file deleted in a clean-up, a path that changed folder, or a reconfigured CDN leave the link pointing at nothing — and in your own browser the cached icon keeps showing for weeks. It is one of the few elements you have to check from outside to know whether it exists.