The hyphen is a connector; it may join “what is similar and also what is disjunctive.it divides as well as marries.” The hyphen connects words, prefixes, and suffixes permanently or temporarily. Certain compound words always contain hyphens. Such hyphens are called orthographic. Examples are merry-go-round, free-for-all, and mother-in-law. For temporary connections, hyphens help prevent ambiguity, clarify meaning, and indicate word breaks at the end of a line. In general, when not otherwise specified, hyphens should be used only as an aid to the reader’s understanding, primarily to avoid ambiguity.
Chicago Manual Of Style Title Case Hyphenated Words
For capitalization of hyphenated compounds in titles, subtitles, subheads, and table.