Before switching a preference, decide whether you want to type markup or see formatting while composing. The toolbar gives you a visible result before sending; markup mode leaves more of the interpretation until delivery.
Start with the toolbar for a short message
Type the message, select the words you want to emphasize, and apply the relevant toolbar option. Slack offers bold, italics, underline, strikethrough, code, quotes, code blocks, and lists. Press Shift+Enter for another line when Enter would send. Message formatting controls
For an illustrative handoff, write:
Equipment handoff
The spare key is in drawer B.
Please confirm collection in this thread.
Bold the first line and format drawer B as inline code only if preserving that exact label helps the reader. The message still needs its instruction; emphasis cannot replace a missing location or next action.
Use Slack's markup when you prefer typing it
With markup mode enabled, the same fictional note could start like this:
*Equipment handoff*
The spare key is in `drawer B`.
_Please confirm collection in this thread._
Slack documents single asterisks for bold. Do not carry over GitHub's double-asterisk convention without checking the result. Use a pair of single backticks for a short literal phrase, and three backticks around a multi-line code block.
Markup mode also changes paste behavior: copied messages paste as plain text, and automatic list formatting is disabled. If numbered or bulleted lines stop turning into lists while typing, check that preference before repeatedly replacing the text.
Adapt a README excerpt to the conversation
A repository heading such as ## Deployment notes should become a short readable label in the message, with the relevant instruction immediately after it. If the source contains a wide table, rewrite the few relevant rows as separate sentences or link to the original document. Preserve the association between each item and its value.
For example, turn a fictional two-column record into “Return point: reception. Collection deadline: Friday at 4 p.m.” Replace those practice values before sending. Do not leave the reader to match values across a broken table.
If the original document belongs on GitHub, keep the full version there. GitHub Markdown syntax covers that destination; Slack can carry the decision and a link to its supporting detail.
Keep app syntax separate from the message box
Slack apps use a format called mrkdwn in supported message fields. Its link syntax includes <url|label>, while Slack's user-facing markup instructions document [label](url) for the composer. Follow the instructions for the surface you are editing. Slack app text formatting
Check the actual delivered message when you next send it through your normal workflow. Confirm that the label, literal code, line breaks, and destination link survived. Correct the message itself if punctuation obscures the instruction.