Bold and italics in YouTube comments

If you use a search engine, you may find out the base rules for styling in YouTube comments, but they never tell you the whole story (for it to actually work in all cases). In fact, at first glance, it appears styling in YouTube comments is broken. But it is not! – read on to see how it can be made to work reliably. Note, however, that bold is currently broken (as 2020-11-09).

Base rules


Enclose the text in a pair of underscores, “_”.


Part of this is _to be in italics_ and other parts not.


Part of this is to be in italics and other parts not.


Enclose the text in a pair of asterisks, “*”.


Part of this is *to be in bold* and other parts not.


Part of this is to be in bold and other parts not.

Bold and italics

Just enclose the inner (italics) in bold, just like any other text.


Combining *_both italics and bold_* is easy.


Combining both italics and bold is easy.

Strike through

Note: This is a poor form of a revision history and it should seldomly be used.

Enclose the text in a pair of dashes (actually minus signs), “-“.


I -wildly guessed- did extensive research to find...


I wildly guessed did extensive research to find…

More rules

Without observing these, the styling may simply silently fail.

There must not be a space at the beginning and end of the enclosed text

That is, immediately after the first underscore or asterisk, there must be a number, letter, or special character. If it is a space, the text styling does not work. In other words, the inner text must not have leading or trailing space.

The same immediately before the last underscore or asterisk.

There must be a space to either side

This sometimes forces you to use the Indian space (from the outdated 1935 Wren & Martin textbook). It is not ideal, but some alternatives are: 1) Leave out the punctuation 2) Use dash/minus to continue into a second part. 3) Use the hair space, Unicode U+200A (“ ”. E.g., it can be entered with Ctrl + Shift + 200A + Return on Linux (e.g. Ubuntu/Cinnamon) and it also works copy-pasting it from this page). 4) Add some content in parentheses (as there is a space before the opening parenthesis). E.g ” (see also XYZ)”.

Example where a space is needed before punctuation in order for the styling to work (bold):

Well, I *lost a pawn* , but it's just a pawn.

Result (note the Indian space between “pawn” and the second comma (“,”)):

Well, I lost a pawn , but it’s just a pawn.

A hard linebreak resets the formatting

For multiline text (where you insert hard line breaks), the formatting must be applied for each line. Hard breaks are necessary in YouTube comments when indenting is to be preserved.

Example where all of the text is to be in italics:

_"One of the spires of Zagreb Cathedral broke off and fell on_
_the Archbishop's palace. ... A part of the roof of the_
_Croatian Parliament building collapsed."_


“One of the spires of Zagreb Cathedral broke off and fell on
the Archbishop’s palace. … A part of the roof of the
Croatian Parliament building collapsed.”

Beware of asterisks and underscores in the original text

Example, in a URL:

en DOT wikipedia DOT org/wiki/Ian_Nepomniachtchi

This is difficult or impossible to get in italics because of the underscore between “Ian” and “Nepomniachtchi”. The workaround is to format in bold (using asterisks) instead.

YouTube breaks stuff, but moves slow

Exhibit 1

On 2020-05-21 YouTube comments broke. After having worked flawlessly for years, now it does not seem possible to have empty lines in YouTube comments (it could be a overreaction to the problem of too many empty lines when using the (physical) Return key). And leading space (for indent) may be removed.

This was observed on Linux (Ubuntu 19.10 (Eoan Ermine), but with Cinnamon as the desktop environment) with Firefox 76.0.1 (current on the date).


For empty lines, the workaround is to add a space on the line that should appear empty. Also, Edit Overflow’s YouTube formatter (button “Transform for YouTube comments”) has also been extended with this workaround such that it can also be used to preserve empty lines.

Exhibit 2

On 2020-07-09 bold in YouTube comments broke – it was rendered as normal text (italics still worked). There didn’t seem to be a workaround.

On 2020-07-30 it worked again (but didn’t a few days prior). It broke again in August 2020 and was broken until 2020-09-28. But then it was promptly broken the same day – as of 2020-10-09 it was still broken.

On 2020-11-01 it started working again (both when adding new comments and old comments with bold formatting (asterisks)), but again only for a single day.

As of 2020-11-09 it is still broken. Why in hell can’t they add a regression test for a simple thing like this????

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