W3C Validation error: general entity "gid" not defined and no default entity

Question

This error has something to do with the link of Linedin.com
I have included the social network links in a PHP include (social-icons.php) and when I try to use HTML standard character like &amp it doesn't change the validation. Here is the validation errors on W3C: http://validator.w3.org/check?uri=http://sneakyrascal.com/theyeastdiet/

Answer 1

Actually if you change all the & with & the website will be validated. Please note the ; after &amp (in your example you didn't write it).