HTML Guide
Attributes in HTML elements need to be separated by space, in this example the first line is invalid and the second one is valid:
<a href="page.php"class="big">link</a>
<a href="page.php" class="big">link</a>Related W3C validator issues
<a> tags can be used to link to an email address using the mailto protocol in the href attribute. Ensure that there is no space in the email address.
<a href="mailto: liza@example.com">This is wrong as it contains an space</a>
<a href="mailto:liza@example.com">This is OK</a>An href attribute on an a element contains an invalid URL that has space characters in the domain.
The domain in a URL cannot contain space characters, for example the following are invalid:
<a href="http://my domain.com">link</a>
<a href="http://my%20domain.com">link</a>Attributes for HTML elements must be defined like name="value". The name may be missing before the =.
Some examples:
<!-- Missing equal sign -->
<p name "value"></p>
<!-- Missing space before the attribute -->
<pname "value"></p>A < character has been found when an attribute was expected instead. Check the syntax of the affected tag, it’s probably malformed and a < character inside has been interpreted as an attribute.
For example, this code might cause this issue:
<!-- Malformed img tag -->
<img src="photo.jpg" alt="smiling cat" < />
<!-- Fixed img tag -->
<img src="photo.jpg" alt="smiling cat" />Attributes for HTML elements must be defined like name="value". A common issue is missing the =, or repeating the " like in these examples:
<!-- Missing equal sign -->
<p name "value"></p>
<!-- Repeated quotes -->
<p name="value""></p>