Existem vários ícones diferentes e até telas de abertura que você pode definir para vários dispositivos. Essa resposta explica como dar suporte a todos eles.
Aqui estão alguns trechos que usei com links relevantes para onde reuni as informações. Consulte meu blog para obter mais informações e mais informações sobre o modelo de projeto Boilerplate da ASP.NET MVC com tudo isso pronto para uso (incluindo arquivos de imagem de amostra).
Adicione a seguinte marcação ao seu cabeçalho html. As seções comentadas são totalmente opcionais. Enquanto as seções não comentadas são recomendadas para cobrir todos os usos de ícones. Não se assuste, mais se for comentários para te ajudar.
<!-- Icons & Platform Specific Settings - Favicon generator used to generate the icons below http://realfavicongenerator.net/ -->
<!-- shortcut icon - It is best to add this icon to the root of your site and only use this link element if you move it somewhere else. This file contains the following sizes 16x16, 32x32 and 48x48. -->
<!--<link rel="shortcut icon" href="favicon.ico">-->
<!-- favicon-96x96.png - For Google TV. -->
<link rel="icon" type="image/png" href="https://stackoverflow.com/content/images/favicon-96x96.png" sizes="96x96">
<!-- favicon-16x16.png - The classic favicon, displayed in the tabs. -->
<link rel="icon" type="image/png" href="https://stackoverflow.com/content/images/favicon-16x16.png" sizes="16x16">
<!-- favicon-32x32.png - For Safari on Mac OS. -->
<link rel="icon" type="image/png" href="https://stackoverflow.com/content/images/favicon-32x32.png" sizes="32x32">
<!-- Android/Chrome -->
<!-- manifest-json - The location of the browser configuration file. It contains locations of icon files, name of the application and default device screen orientation. Note that the name field is mandatory.
https://developer.chrome.com/multidevice/android/installtohomescreen. -->
<link rel="manifest" href="https://stackoverflow.com/content/icons/manifest.json">
<!-- theme-color - The colour of the toolbar in Chrome M39+
http://updates.html5rocks.com/2014/11/Support-for-theme-color-in-Chrome-39-for-Android -->
<meta name="theme-color" content="#1E1E1E">
<!-- favicon-192x192.png - For Android Chrome M36 to M38 this HTML is used. M39+ uses the manifest.json file. -->
<link rel="icon" type="image/png" href="https://stackoverflow.com/content/icons/favicon-192x192.png" sizes="192x192">
<!-- mobile-web-app-capable - Run Android/Chrome version M31 to M38 in standalone mode, hiding the browser chrome. -->
<!-- <meta name="mobile-web-app-capable" content="yes"> -->
<!-- Apple Icons - You can move all these icons to the root of the site and remove these link elements, if you don't mind the clutter.
https://developer.apple.com/library/safari/documentation/AppleApplications/Reference/SafariHTMLRef/Introduction.html#//apple_ref/doc/uid/30001261-SW1 -->
<!-- apple-mobile-web-app-title - The name of the application if pinned to the IOS start screen. -->
<!--<meta name="apple-mobile-web-app-title" content="">-->
<!-- apple-mobile-web-app-capable - Hide the browsers user interface on IOS, when the app is run in 'standalone' mode. Any links to other pages that are clicked whilst your app is in standalone mode will launch the full Safari browser. -->
<!--<meta name="apple-mobile-web-app-capable" content="yes">-->
<!-- apple-mobile-web-app-status-bar-style - default/black/black-translucent Styles the IOS status bar. Using black-translucent makes it transparent and overlays it on top of your site, so make sure you have enough margin. -->
<!--<meta name="apple-mobile-web-app-status-bar-style" content="black">-->
<!-- apple-touch-icon-57x57.png - Android Stock Browser and non-Retina iPhone and iPod Touch -->
<link rel="apple-touch-icon" sizes="57x57" href="https://stackoverflow.com/content/images/apple-touch-icon-57x57.png">
<!-- apple-touch-icon-114x114.png - iPhone (with 2× display) iOS = 6 -->
<link rel="apple-touch-icon" sizes="114x114" href="https://stackoverflow.com/content/images/apple-touch-icon-114x114.png">
<!-- apple-touch-icon-72x72.png - iPad mini and the first- and second-generation iPad (1× display) on iOS = 6 -->
<link rel="apple-touch-icon" sizes="72x72" href="https://stackoverflow.com/content/images/apple-touch-icon-72x72.png">
<!-- apple-touch-icon-144x144.png - iPad (with 2× display) iOS = 6 -->
<link rel="apple-touch-icon" sizes="144x144" href="https://stackoverflow.com/content/images/apple-touch-icon-144x144.png">
<!-- apple-touch-icon-60x60.png - Same as apple-touch-icon-57x57.png, for non-retina iPhone with iOS7. -->
<link rel="apple-touch-icon" sizes="60x60" href="https://stackoverflow.com/content/images/apple-touch-icon-60x60.png">
<!-- apple-touch-icon-120x120.png - iPhone (with 2× and 3 display) iOS = 7 -->
<link rel="apple-touch-icon" sizes="120x120" href="https://stackoverflow.com/content/images/apple-touch-icon-120x120.png">
<!-- apple-touch-icon-76x76.png - iPad mini and the first- and second-generation iPad (1× display) on iOS = 7 -->
<link rel="apple-touch-icon" sizes="76x76" href="https://stackoverflow.com/content/images/apple-touch-icon-76x76.png">
<!-- apple-touch-icon-152x152.png - iPad 3+ (with 2× display) iOS = 7 -->
<link rel="apple-touch-icon" sizes="152x152" href="https://stackoverflow.com/content/images/apple-touch-icon-152x152.png">
<!-- apple-touch-icon-180x180.png - iPad and iPad mini (with 2× display) iOS = 8 -->
<link rel="apple-touch-icon" sizes="180x180" href="https://stackoverflow.com/content/images/apple-touch-icon-180x180.png">
<!-- Apple Startup Images - These are shown when the page is loading if the site is pinned https://gist.github.com/tfausak/2222823 -->
<!-- apple-touch-startup-image-1536x2008.png - iOS 6 & 7 iPad (retina, portrait) -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-1536x2008.png"
media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 2)">
<!-- apple-touch-startup-image-1496x2048.png - iOS 6 & 7 iPad (retina, landscape) -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-1496x2048.png"
media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 2)">
<!-- apple-touch-startup-image-768x1004.png - iOS 6 iPad (portrait) -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-768x1004.png"
media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 1)">
<!-- apple-touch-startup-image-748x1024.png - iOS 6 iPad (landscape) -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-748x1024.png"
media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 1)">
<!-- apple-touch-startup-image-640x1096.png - iOS 6 & 7 iPhone 5 -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-640x1096.png"
media="(device-width: 320px) and (device-height: 568px) and (-webkit-device-pixel-ratio: 2)">
<!-- apple-touch-startup-image-640x920.png - iOS 6 & 7 iPhone (retina) -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-640x920.png"
media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 2)">
<!-- apple-touch-startup-image-320x460.png - iOS 6 iPhone -->
<link rel="apple-touch-startup-image"
href="https://stackoverflow.com/content/images/apple-touch-startup-image-320x460.png"
media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 1)">
<!-- Windows 8 Icons - If you add an RSS feed, revisit this page and regenerate the browserconfig.xml file. You will then have a cool live tile!
browserconfig.xml - Windows 8.1 - Has been added to the root of the site. This points to the tile images and tile background colour. It contains the following images:
mstile-70x70.png - For Windows 8.1 / IE11.
mstile-144x144.png - For Windows 8 / IE10.
mstile-150x150.png - For Windows 8.1 / IE11.
mstile-310x310.png - For Windows 8.1 / IE11.
mstile-310x150.png - For Windows 8.1 / IE11.
See http://www.buildmypinnedsite.com/en and http://msdn.microsoft.com/en-gb/library/ie/dn255024%28v=vs.85%29.aspx. -->
<!-- application-name - Windows 8+ - The name of the application if pinned to the start screen. -->
<!--<meta name="application-name" content="">-->
<!-- msapplication-TileColor - Windows 8 - The tile colour which shows around your tile image (msapplication-TileImage). -->
<meta name="msapplication-TileColor" content="#5cb95c">
<!-- msapplication-TileImage - Windows 8 - The tile image. -->
<meta name="msapplication-TileImage" content="/content/images/mstile-144x144.png">
Meu arquivo browserconfig.xml. Explicação completa acima.
<?xml version="1.0" encoding="utf-8"?>
<browserconfig>
<msapplication>
<tile>
<square70x70logo src="/Content/Images/mstile-70x70.png"/>
<square150x150logo src="/Content/Images/mstile-150x150.png"/>
<square310x310logo src="/Content/Images/mstile-310x310.png"/>
<wide310x150logo src="/Content/Images/mstile-310x150.png"/>
<TileColor>#5cb95c</TileColor>
</tile>
</msapplication>
</browserconfig>
Meu arquivo manifest.json. Explicação completa acima.
{
"name": "ASP.NET MVC Boilerplate (Required! Update This)",
"icons": [
{
"src": "\/Content\/icons\/android-chrome-36x36.png",
"sizes": "36x36",
"type": "image\/png",
"density": "0.75"
},
{
"src": "\/Content\/icons\/android-chrome-48x48.png",
"sizes": "48x48",
"type": "image\/png",
"density": "1.0"
},
{
"src": "\/Content\/icons\/android-chrome-72x72.png",
"sizes": "72x72",
"type": "image\/png",
"density": "1.5"
},
{
"src": "\/Content\/icons\/android-chrome-96x96.png",
"sizes": "96x96",
"type": "image\/png",
"density": "2.0"
},
{
"src": "\/Content\/icons\/android-chrome-144x144.png",
"sizes": "144x144",
"type": "image\/png",
"density": "3.0"
},
{
"src": "\/Content\/icons\/android-chrome-192x192.png",
"sizes": "192x192",
"type": "image\/png",
"density": "4.0"
}
]
}
Uma lista dos arquivos no projeto (observe que os nomes desses arquivos são importantes se você decidir colocar alguns deles na raiz do seu projeto para evitar o uso das meta tags acima):
favicon.ico
browserconfig.xml
Content/Images/
android-chrome-144x144.png
android-chrome-192x192.png
android-chrome-36x36.png
android-chrome-48x48.png
android-chrome-72x72.png
android-chrome-96x96.png
apple-touch-icon.png
apple-touch-icon-57x57.png
apple-touch-icon-60x60.png
apple-touch-icon-72x72.png
apple-touch-icon-76x76.png
apple-touch-icon-114x114.png
apple-touch-icon-120x120.png
apple-touch-icon-144x144.png
apple-touch-icon-152x152.png
apple-touch-icon-180x180.png
apple-touch-icon-precomposed.png (180x180)
favicon-16x16.png
favicon-32x32.png
favicon-96x96.png
favicon-192x192.png
manifest.json
mstile-70x70.png
mstile-144x144.png
mstile-150x150.png
mstile-310x150.png
mstile-310x310.png
apple-touch-startup-image-1536x2008.png
apple-touch-startup-image-1496x2048.png
apple-touch-startup-image-768x1004.png
apple-touch-startup-image-748x1024.png
apple-touch-startup-image-640x1096.png
apple-touch-startup-image-640x920.png
apple-touch-startup-image-320x460.png
Sobrecarga total
Se você retirar os comentários, terá 3 KB de HTML extra, se não der suporte a telas iniciais de 1,5 KB. Se você estiver usando compactação GZIP em seu conteúdo HTML, o que todos deveriam estar fazendo atualmente, isso deixa você com cerca de 634 bytes de sobrecarga por solicitação para suportar todas as plataformas ou 446 bytes sem telas iniciais. Pessoalmente, acho que vale a pena oferecer suporte a dispositivos IOS, Android e Windows, mas é sua escolha, estou apenas dando as opções!
Observação lateral sobre o ícone da web atual / tela inicial / situação das configurações
Esta situação com ícones específicos de fornecedores, telas de abertura e tags especiais para controlar o navegador da web ou ícones fixados é ridícula. Em um mundo perfeito, todos nós usaríamos um arquivo favicon.svg que poderia parecer bom em qualquer tamanho e poderia ser colocado na raiz da página. Apenas o FireFox oferece suporte para isso no momento da escrita (consulte CanIUse.com ).
No entanto, os ícones não são a única configuração atualmente, existem várias outras configurações específicas do fornecedor (mostradas acima), mas um arquivo favicon.svg cobriria a maioria dos casos de uso.
Atualizar
Atualizado para incluir a nova versão Android / Chrome M39 + opções de favicon / tema. Curiosamente, eles adotaram uma abordagem semelhante à da Microsoft, mas estão usando um arquivo JSON em vez de XML.