To type an em dash (—): On Mac:

• Press Option + Shift + Hyphen (-) keys together.

On Windows:

• Hold the Alt key and type 0151 on the numeric keypad, then release the Alt key.
• Alternatively, in Microsoft Word, typing two hyphens between words (like--this) will automatically convert to an em dash.
• You can also press Windows + . (period) to open the emoji/symbol picker and select the em dash from Symbols.

Additional ways include using the "Insert Symbol" menu in word processors or setting up auto-replace shortcuts. The en dash (–), which is shorter than the em dash, has different shortcuts. These methods cover most devices and apps to type an em dash conveniently.