A line break is the process of wrapping text from the current line to the next. In HTML, <br> creates an explicit line break, while CSS properties word-break and overflow-wrap control automatic line breaking behavior.

CJK text (Chinese, Japanese, Korean) can break at almost any character position since words are not separated by spaces. English text, by contrast, should not break in the middle of a word. CJK typesetting rules books cover line break prohibition rules.

Japanese has specific line break rules called kinsoku: punctuation must not appear at the start of a line, and bracket pairs must not be split. The CSS line-break property controls the strictness of these rules.

In programming, differences in newline codes (LF, CR, CRLF) can cause subtle bugs. Web frontend development books explain text display control in detail.