There are full on character encoding introductions. I think an easy to approach one is: https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-so

There are full on character encoding introductions. I think an easy to approach one is: https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/ https://www.joelonsoftware.com/2003/10/08/the-absolute-minim... Basically, ascii is encoded as integers. '32' represents a space. However, ascii is quite limited and if you want non-US-centric characters, you need to use other character sets. For a myriad of reasons, once you go into unicode (the Universal Character Set) there are lots more options for characters. For example, there are multiple whitespace characters. http://jkorpela.fi/chars/spaces.html http://jkorpela.fi/chars/spaces.html These exist to give different widths or other adjustments to text that is non-ascii. What likely happened in the post (and what did happen to me) is copy-pasting from some document that changed a normal ascii space (that Ruby would expect and know how to deal with) into a unicode character that Ruby interprets as any other character. It would be like having a stray 'g' in the line, but you, as a developer, don't see it. Fun :)