Whitespace is good, but with Unicode you can do even better by using invisible characters such as ZERO WIDTH SPACE (U+200B) and ZERO WIDTH JOINER (U+200D). I once made a proof of concept[1] using those two characters. It can converts arbitrary data into invisible text by using U+200B as bit 0 and U+200D as bit 1.<p>Most platforms (Twitter, Reddit, Hacker News) accepts those characters so you can paste invisible messages there. The illusion falls down as soon as you use a low-level text editor such as vim which marks exotic characters in a specific manner (by displaying their hexadecimal codepoint, as it happens). This is where whitespace can be more powerful, given its mainstream usage​‍​​‍‍‍‍​‍‍​‍​​​​​‍​‍‍​​​​‍​​​​​​‍‍​‍​​​​‍‍​​‍​‍​‍‍​‍‍​​​‍‍​‍‍​​​‍‍​‍‍‍‍​​‍​​​​​​‍‍‍​‍​​​‍‍​‍​​​​‍‍​​‍​‍​‍‍‍​​‍​​‍‍​​‍​‍​​‍​‍‍‍​​​‍​​​​​​‍​​​‍‍‍​‍‍​‍‍​​​‍‍​​​​‍​‍‍​​‍​​​​‍​​​​​​‍‍‍​‍​​​‍‍​‍‍‍‍​​‍​​​​​​‍‍‍​​‍‍​‍‍​​‍​‍​‍‍​​‍​‍​​‍​​​​​​‍‍‍​‍​​​‍‍​‍​​​​‍‍​​​​‍​‍‍‍​‍​​​​‍​​​​​​‍‍‍‍​​‍​‍‍​‍‍‍‍​‍‍‍​‍​‍​​‍​​​​​​‍‍‍​‍‍‍​‍‍​​‍​‍​‍‍‍​​‍​​‍‍​​‍​‍​​‍​​​​​​‍‍​​​‍‍​‍‍‍​‍​‍​‍‍‍​​‍​​‍‍​‍​​‍​‍‍​‍‍‍‍​‍‍‍​‍​‍​‍‍‍​​‍‍​​‍​​​​​​‍‍​​‍​‍​‍‍​‍‍‍​​‍‍​‍‍‍‍​‍‍‍​‍​‍​‍‍​​‍‍‍​‍‍​‍​​​​​‍​​​​​​‍‍‍​‍​​​‍‍​‍‍‍‍​​‍​​​​​​‍‍​​​​‍​‍‍​​​‍‍​‍‍​‍​​​​‍‍​‍​​‍​‍‍​​‍​‍​‍‍‍​‍‍​​‍‍​​‍​‍​​‍​​​​​​‍‍‍​​‍​​‍‍​​‍​‍​‍‍​​​​‍​‍‍​​‍​​​‍‍​‍​​‍​‍‍​‍‍‍​​‍‍​​‍‍‍​​‍​​​​​​‍‍‍​‍​​​‍‍​‍​​​​‍‍​‍​​‍​‍‍‍​​‍‍.<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;foobuzz&#x2F;ium" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;foobuzz&#x2F;ium</a>