The word-break CSS property defines if line breaks are allowed in words. It only allows breaking between any two characters or not breaking at all.
word-break is primarily useful when working with East Asian languages. If you are looking for the best way to hyphenate English characters, use the hyphens property.
word-break: normal; /* don't break words */ word-break: break-all; /* break at any character */
The default normal doesn't break words, while break-all allows breaking between any two characters. According to the specification, it is most useful in CJK (Chinese, Japanese Korean) languages when mixed with English for example, to better distribute text. keep-all affects only Chinese Japanese and Korean languages. It makes those languages behave like English and break only at spaces.
Browser Support: Full support for break-all. Partial support for keep-all. See the word-break compatibility table for more details.
break-all will break lines within words always, unless there happens to be a space at the end of the line.
word-break vs overflow-wrap (word-wrap)
word-break: break-all breaks any word at the end of the line,
overflow-wrap: break-word will break only long words, that would overflow otherwise. See the overflow-wrap's page for more details.