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This is probably related to whether one should capitalize Internet or not. I am looking for the correct spelling of wifi when referring to a wireless connection to the Internet. I want to tell the users of my iPhone app that they cannot use their cellular network to watch the HD videos.

If I use the capitalized and hyphenated version as seen on Wikipedia, will I be referring to the Wi-Fi brand rather than the concept of wifi?

"Wi-Fi" is a trademark of the Wi-Fi Alliance and the brand name for products using the IEEE 802.11 family of standards.

Some dude on Meta.stackoverflow made this claim with no explanation:

WiFi" is a bit better than "wifi" as it asserts the etymology, compare history of usage of "hifi" from which it derives. – Steve-o Aug 29 at 3:59

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The Wi-Fi Alliance is just a trade association. They won't come knocking on your door in the middle of the night if you use their terminology. They're only interested in shutting out comptetition from any major global manufacturers who don't want to join them. Anyway, you've answered your own question by the mere fact that you happily wrote wifi twice in the first paragraph before wondering about capitalisation/hyphenation. Use what comes naturally to mind. – FumbleFingers Sep 9 '11 at 0:10
My experience (non-native speaker from Europe) is: "WiFi" is rarely used, most people/places refer to it as "WLAN". I'm curous: does anyone else observe this outside of the US? In German language text I see "WLAN" being used exclusively and in English language text around Europe there seems to be a strong tendency towards "WLAN". – Joachim Sauer Sep 9 '11 at 6:17
@Joachim: WLAN is uncommon in Swedish (which is a Germanic language). I suspect the Nordic languages borrow more frequently from English than the ones further south. We also don't dub movies. :) – Jonas Byström Sep 9 '11 at 10:40
This reminds me very much of this question: Is “blah blah blah” the most common spelling? – hippietrail Sep 14 '12 at 14:46
@Matthew: This was nearly 3 years ago, and I honestly can't remember for certain, but I think it's unlikely I personally specified "Too Localised" (which is no longer available). I probably said it was "Not Constructive" (also no longer available), which would be in line with the comment I made at the time. And it just so happened TL was cited more often by the other 4 closevoters. IMHO the question is utterly pointless, because no-one is "in charge" of defining correct usage here, and the idea of the Wi-Fi Alliance "owning" that particular representation is frankly risible. – FumbleFingers Jun 23 '14 at 20:03
up vote 2 down vote accepted

Since you have an iPhone app and it would seem that Apple/iPhone use the term "Wi-Fi" throughout then I would use the same for consistency. iPhone users expect to see "Wi-Fi".

However, there could be a regional difference...

Note: iOS devices sold in China may use the term Wireless LAN (WLAN) instead of Wi-Fi.

Reference: http://support.apple.com/kb/ts1398

(EDIT: For comparison, my Nokia E65 (sold in the UK) uses the terms "WLAN" or "Wireless LAN" exclusively, no mention of "Wi-Fi" or its derivatives.)

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In the past it was "Wi-Fi", but the current trend is toward "wifi".

It's a little like e-Mail => eMail => email.

December 2015 update: A Google search now results in 41% more occurences of "wi-fi" than "wifi". Apparently the trend has reversed.

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Could you provide some kind of reference to back up this claim please? – hippietrail Sep 14 '12 at 14:43
This question was closed, inappropriately in my opinion, because it is "unlikely to help any future visitors." But you can Google "wi-fi" and "wifi", and you'll find that wifi has more hits. "Wi-fi" used to have more hits. – xpda Sep 17 '12 at 3:27
I believe this question should be reopened. Can we say two years later that this trend been confirmed? – Mari-Lou A Sep 11 '13 at 8:06
Even 4 years later with 27,000 views, this question is still "unlikely to help any future visitors". – xpda Mar 31 '15 at 18:29

According to publications like PC Magazine which would be more likely to use the "correct" spelling, the word is spelled:


A wireless local area network (WLAN) technology that conforms to the IEEE 802.11 standard. Wi-Fi is the wireless counterpart to the wired Ethernet network, which is the ubiquitous local area network (LAN) technology used in companies and homes worldwide. A Wi-Fi logo from the Wi-Fi Alliance certifies that network devices comply with the IEEE 802.11 standards.

However, this page from Princeton spells it WiFi. Based on a quick Google search, most official sites (such as Starbucks) use either WiFi or Wi-Fi. Since there is so much variation, wifi looks fine as it is, and people understand the forms wifi, WiFi, Wi-Fi and possibly Wifi, you could use any of them and still be fine. The key to your use is that you are aiming towards being understood, not necessarily maintaining the trademark. (If we all maintained trademarks, we wouldn't refer to Blackberries instead of Blackberry mobile devices.)

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I really think this is one case where even in quotes, the word "correct" is a bit misplaced. Also note that even after many decades, usage for the analogous hifi/hi-fi is still split pretty much 50-50, so it ain't going anywhere fast. – FumbleFingers Sep 9 '11 at 0:23
I think all variations of wifi are understandable. I'm not worried about sounding strange to my users. I'm just wondering if a particular variant would result in legal issues because it refers to a company's trademark rather than a general concept. – JoJo Sep 9 '11 at 0:25
Prepare yourself for the possibility that the freelance journalist writing for PC Magazine arbitrarily chose the orthography that they preferred and nobody cared terribly much. Whether that makes it "correct" or not I think is a largely pointless and/or unanswerable question... – Neil Coffey Sep 9 '11 at 1:18
It is highly unlikely that PC Magazine left its style decision for Wi-Fi to a freelance journalist who happened to be writing the entry for that topic in its "PC Encyclopedia"—especially since the piece was posted in the days when PC Magazine still had (I believe) a copyediting staff. I know for a fact that PC World (which for years was the biggest print rival of PC Mag) maintained a house word list that was several hundred pages long, and that Wi-Fi appeared on that list only after considerable research and consultation with various in-house editors. – Sven Yargs Apr 1 '15 at 0:56

The correct spelling is Wi-Fi even if wifi is most used.

Google Trends clearly shows this: wifi vs Wi-Fi on google trends

If it's technical document, I would use Wi-Fi. But, if SEO is very important, I would use wifi (+other keywords to create a long tail keyword).

Valeria (anyway, on the Tanaza website we use only Wi-Fi)

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