If you prefer to always format your messages with markup instead of Slack's built-in formatting on your desktop, you can set a message formatting preference.
What to expect
When you choose to set your preference to format messages with markup, there are a few limitations to bear in mind:
Formatting will be applied to messages after you send them.
Messages that you copy and paste will appear in plain text.
Automatic formatting for bulleted, numbered and indented lists is not supported.
Manage your message formatting preference
From your desktop, click your profile picture in the sidebar.
Select Preferences from the menu.
Select Advanced.
Under Input options, tick or untick the box next to Format messages with markup.
Markup
Once you’ve set your formatting preference, you can use the following markup actions to format your messages in Slack.
Formatting
Description
Surround text with asterisks: *your text*
Surround text with underscores: _your text_
Surround text with tildes: ~your text~
Surround text with backticks: `your text`
Add an angled bracket in front of text: >your text
Surround text with three backticks: ```your text```
Surround text with brackets, then surround the link with parentheses: [your text](the link)