Sometimes the use of invisible characters is needed in order to trick certain mobile devices into not detecting dates within text.
Within your account however, there is the possibility that using these invisible characters at the beginning of a hyperlink inside an <a> tag, could cause the clicks on that link to not be included in your reports.
This is obviously undesirable, so one must be careful to not use the invisible character in such a location in your HTML. The invisible character is as follows:
This is the markup for the invisible character: ​
As such, having these characters inside web links can cause the link to break. Here's an example of what not to do...
<a href="​http://www.linkURL.com">This link will break</a>