W3C Validator Unicode Byte-Order Mark Error

Okay, so you've published your site and validated your code to perfection, except for one error: "The unicode byte-order mark (BOM) in UTF-8 encoded files is known to cause problems for some text editors and older browsers. You may want to consider avoiding its use until it is better supported."

So, what in the world is this?

A byte-order mark (BOM) is a special character contained in the first three bytes of a text document, used to identify that specific file as UTF-8. Sounds good so far but what about older browsers or text editors that do not understand the BOM? If an old browser/text editor reads a file with the BOM character, a weird symbol could appear at the top of the file.

No, it's not the end of the world, but unwanted characters at the top of a page could break CSS styles, confuse the viewer, and gives the web page an unprofessional, uncared-for look. The solution is to save the text file as UTF-8, but simply leave out the BOM.

Most modern text editors have the capability to save a document as UTF-8, either with or without the BOM.

Creative Commons License