When to use hyphen between words?

Use a hyphen to connect two or more Words that function together as a single adjective before a noun, such as "well-known author" or "high-speed train." Additionally, hyphens are used in compound numbers (twenty-one, thirty-five) and to avoid confusion in phrases, like "re-sign" versus "resign." They are also helpful in breaking Words at the end of a line. Always check for specific style guides, as hyphenation rules can vary.