wordbreaking

Word breaking is the process of determining where a line of text may be broken to wrap content to a new line. It identifies permissible break points between characters, between words, and in some cases within words. In languages that use spaces to separate words, line breaks typically occur at whitespace or punctuation. In languages without explicit word boundaries, such as Chinese or Japanese, line breaking relies on scripts' typographic rules to determine boundaries between characters. Hyphenation is related but distinct: it refers to breaking a word at syllable or morpheme boundaries, often with a hyphen inserted. Soft hyphen characters and zero-width joiners can influence potential break points without visible marks.

Break rules are implemented by line-breaking algorithms. In Unicode, the line breaking algorithm (UAX #14) defines where breaks may occur for rendering text, while UAX #29 addresses word boundaries for segmentation, useful for NLP. Common approaches include greedy wrapping, which chooses the first permissible break from the current line, and optimal wrapping, which minimizes raggedness using dynamic programming. Font metrics, writing direction, and script-specific rules affect decisions. For display, engines consider hard vs soft breaks, the presence of non-breaking spaces, and hyphenation dictionaries or patterns; CJK line breaking uses character-based rules that differ from alphabetic languages.

In practice, word breaking affects text layout in word processors, web browsers, and typesetting systems. It influences readability, justification, and accessibility. Developers may tune behavior with typographic settings or Unicode properties, and designers must account for multilingual content and scripts with different breaking conventions.