How to Italicise Text in Slack (Ctrl+I / Cmd+I)

Select text in the Slack message box and press Ctrl+I, or Cmd+I on macOS. Wrapping the words in underscores, like _this_, produces the same italic result as you type. **Underscores, not asterisks — and this is the single most common Slack formatting mistake.** Standard markdown accepts either for italic. Slack accepts only underscores, having assigned single asterisks to bold instead. Someone typing *emphasis* expecting italics gets bold, which is a confusing failure because the message is formatted, just not the way they intended. Using Ctrl+I avoids ever having to remember which character Slack claimed for which style. **Italic reads differently in chat than in prose.** In a document, italics signal titles, foreign terms and light emphasis. In a fast-moving channel they mostly serve one of two jobs: marking an aside that is not part of the main point, or carrying tone — the dry qualifier, the thing said with a raised eyebrow. Both work because italic is quieter than bold, and that quietness is the entire point. Reaching for bold when you meant an aside overstates it. **Formatting combines.** Italic sits alongside bold and strikethrough on the same selection, so a phrase can be bold italic without anything special. Applying both with two keystrokes is considerably easier than working out the nested character syntax, which in Slack's non-standard scheme is genuinely fiddly to get right first time. **Where it does not apply.** Inline code and code blocks show characters literally, so italic formatting has no effect inside them — an underscore in a variable name stays an underscore, which is exactly the behaviour you want when sharing a snippet where `some_variable_name` must survive intact. This is one of the better arguments for wrapping identifiers in code formatting even when they are short: it protects them from being reinterpreted as markup. **Underscores inside words are left alone.** Slack does not italicise the middle of `file_name_here`, because the underscores are not at a word boundary. That is sensible behaviour and it means most technical text survives being pasted into a channel without formatting damage. The failure case is rarer than the equivalent in stricter markdown implementations. **If nothing happens**, the message box has lost focus, or nothing is selected. Slack's formatting shortcuts act on the composer and on a selection within it. With only a cursor placed, the shortcut turns italic on for whatever you type next rather than transforming anything already there — which looks like nothing happening until you start typing. **A cross-application caution.** Copying italic text out of Slack into a document usually preserves the formatting, because both understand rich text. Copying it into a plain-text field — a terminal, a commit message, a code comment — drops the styling entirely and leaves the bare words. That is normally fine, but it is worth remembering when the italics were carrying the distinction between a quoted phrase and your own, since without them the sentence can read as saying something you did not mean. **Italic and emphasis in accessibility terms.** Screen readers do not announce italic text differently by default, so emphasis conveyed only through styling is emphasis some readers will not receive. For anything where the distinction genuinely changes the meaning rather than the tone, saying it in words is more reliable than relying on the visual treatment alone.