<p>I am a big time user of using double quotes in PHP so that I can interpolate variables rather than concatenating strings. As a result, when I am generating HTML I often use single quotes for setting tag fields. For example:</p>

<pre><code>$html = "&lt;input type='text' name='address' value='$address'&gt;";
</code></pre>

<p>Now this is far more readable to me than either</p>

<pre><code>$html = "&lt;input type=\"text\" name=\"address\" value=\"$address\"&gt;";
</code></pre>

<p>or</p>

<pre><code>$html = '&lt;input type="text" name="address" values="' . $address . '"&gt;' ;
</code></pre>

<p>From brief searches I have heard people saying that single quotes for HTML fields is not recognized by EVERY browser. Thus I am wondering what browsers would have problems recognizing single quote HTML?</p>

This is similar to
When did single quotes in HTML become so popular?
. Single quotes around attributes in HTML are and always have been permitted by
the specification
. I don't think any browsers wouldn't understand them.