Windows (Word/Office): Type `2014` then press `Alt+X`
Windows (Alt code): Hold `Alt`, type `0151` on the numeric keypad, release `Alt`
macOS (Unicode): Press `Option` + `Shift` + `-`
macOS (Character Viewer): Press `Control` + `Command` + `Space`, search “em dash”, insert
Linux (Unicode): Press `Ctrl` + `Shift` + `U`, type `2014`, press `Enter`
HTML: `—`
CSS: `2014` or `2014` in `content`
LaTeX: `—` or `textemdash` (with the appropriate package if needed)
Microsoft Word (Insert symbol): Insert → Symbol → More Symbols → select em dash → Insert