I hate to be the bearer of bad tidings, but should you start working with other languages, you'll soon discover that there are many invisible characters and they can really put a monkeywrench in the works at times. One of the most well-known among these is the zero-width space (ZWS) character. It's an invisible character that does not even occupy a space on the screen! Meanwhile, said character affects pattern matching (the word is no longer spelled the same if it has a ZWS in the middle of it), it affects such things as word-wrapping, especially common in unspaced languages like Thai, Lao, Karen, Burmese, etc., and can generally be a nuisance if unexpected and/or the programmer is too naive to account for its existence.

And it's rumored (probably quite true) that various three-letter governmental organizations use the zero-width space in English texts, such as on their websites, placed randomly throughout the text in a fingerprint fashion to track people. Text exactly matching what their server served on a particular occasion can be linked back to the one thus served by this invisible fingerprint. So, it may be worthwhile to purge texts of this sly character.

And there are others: thin spaces, hair spaces, etc.--over 20 of these invisible characters in the unicode spectrum.