According to [Can I use](http://caniuse.com/#feat=user-select-none), the `user-select` is currently supported in all browsers except Internet Explorer 9 and earlier versions (but sadly *still* needs a vendor prefix).
---
All of the correct CSS variations are:
<!-- begin snippet: js hide: false -->
<!-- Note: -khtml- prefix is not required, see http://stackoverflow.com/questions/6687680/what-compatibility-do-i-lose-when-dropping-the-khtml-vendor-prefix -->
<!-- language: lang-css -->
.noselect { -webkit-touch-callout: none; /* iOS Safari */ -webkit-user-select: none; /* Safari */ -khtml-user-select: none; /* Konqueror HTML */ -moz-user-select: none; /* Firefox */ -ms-user-select: none; /* Internet Explorer/Edge */ user-select: none; /* Non-prefixed version, currently supported by Chrome and Opera */ }
<!-- language: lang-html -->
<p> Selectable text. </p> <p class="noselect"> Unselectable text. </p>
<!-- end snippet -->
---
Note that it's a **non-standard feature** (i.e. not a part of any specification). It is not guaranteed to work everywhere, and there might be differences in implementation among browsers and in the future browsers can drop support for it.
--- More information can be found in [Mozilla Developer Network documentation](https://developer.mozilla.org/en-US/docs/Web/CSS/user-select).

**UPDATE January, 2017:**
According to [Can I use](http://caniuse.com/#feat=user-select-none), the `user-select` is currently supported in all browsers except Internet&nbsp;Explorer 9 and earlier versions (but sadly *still* needs a vendor prefix).
---
All of the correct CSS variations are:
<!-- begin snippet: js hide: false -->
<!-- Note: -khtml- prefix is not required, see http://stackoverflow.com/questions/6687680/what-compatibility-do-i-lose-when-dropping-the-khtml-vendor-prefix -->
<!-- language: lang-css -->
.noselect { -webkit-touch-callout: none; /* iOS Safari */ -webkit-user-select: none; /* Safari */ -khtml-user-select: none; /* Konqueror HTML */ -moz-user-select: none; /* Firefox */ -ms-user-select: none; /* Internet Explorer/Edge */ user-select: none; /* Non-prefixed version, currently supported by Chrome and Opera */ }
<!-- language: lang-html -->
<p> Selectable text. </p> <p class="noselect"> Unselectable text. </p>
<!-- end snippet -->
---
Note that it's a **non-standard feature** (i.e. not a part of any specification). It is not guaranteed to work everywhere, and there might be differences in implementation among browsers and in the future browsers can drop support for it.
--- More information can be found in [Mozilla Developer Network documentation](https://developer.mozilla.org/en-US/docs/Web/CSS/user-select).