Whitespace characters

Whitespace characters denote the empty space between the characters you can actually see. 

The most common whitespace character is the word space. This is the one you get when you press the space bar.

The above holds especially true online. Web developers have a tendency to cram as much information on your screen as possible.

However, the more crowded a composition, the less weight is carried by each individual element. When designing a website or a document, you can use whitespace characters to distinguish important information.

In many places online (particularly social media), you’re limited to the whitespace characters designated by Unicode.

Using them effectively can help your writing seem more authoritative.

Sometimes, people add two spaces after a period. There's a logic behind this — as the elements of your writing get bigger, so does the white space between them.

letters → words → sentences → paragraphs

However, a period is mostly white space. So sentences already have more space between them than words. The type designer of your chosen typeface will have taken this into account.

The word space also tells your word processor or web browser when it’s okay to break onto another line — but this isn’t always what you want.

If it’s important to the flow of your writing that two words never be apart, you should insert a no-break space. You can space two words, like normal, without the possibility of them being on separate lines.

These two types of spaces are pretty much the same. Just like the hair space, they’re used to create a little extra space between characters.

Both are roughly one sixth of an em in width. One specific use of the thin space is for separating quotes in nested quotations:

Clive told me that “Prof. Reginald said, ‘Don't use nested quotations.’ ”

A figure space is used solely for spacing fixed-width numerals. Its width is the same as one of the numerals.

The ideographic space, similar to the figure space, is used with fixed-width CJK (Chinese, Japanese, and Korean) characters.

The em space is the width of a capital M, which also happens to be the height of most fonts.

The en space is half the width of an em.

This isn’t really a space. It’s meant to represent a braille pattern with six non-raised dots, so it displays as blank or sometimes six hollow dots. ⠀

This means you can use this space in places where you normally can’t, like in URLs.

The paradoxically named zero-width space lets your browser know when it’s okay to break a word onto a new line without hyphenating it.

Useful, maybe, but the ability to use an invisible character with no width has serious cyber security implications.

Hackers could create usernames, emails addresses, and websites that look identical to a human, but different to computers. Luckily, zero-width spaces are prohibited in email addresses or domain names — and it’s a well-known issue.

On the upside, there are a few genuinely useful things you can do with a zero-width space:

This idea comes from cyber-security guy Zach Aysan.

If your company has a leaker, you can add zero-width spaces to sensitive documents — hidden in different places for each of the recipients.

Once the material is leaked, you can check it for zero-width spaces to find the identity of the leaker.

You can use zero-width spaces to hide an encoded binary message in a piece of text. 

For instance: T​h​e​re is​ a ​h​i​d​d​e​n e​moji ​in ​th​i​s.