Although Slack is replacing email for a number of use cases in offices all over the world, there are still some things that differentiate the two. Most email interfaces contain some sort of formatting bar that allow you to bold, italicize, or block quotes to your text, however there is no equivalent toolbar in Slack’s messaging interface. That does not mean, you can not format your text, you just need to know the proper commands.

*bold* will show as bold
_itaic_ will show as italic
~strikethrough~ will show as strikethrough
>will indent a line
>>> will indent multiple paragraphs

For the engineering crowd there are even options for formatting code blocks
`in-line` will create a code block that is inline with your message
` ` ` fixed width ` ` ` will create a pre-formatted block below your text