Slack markdown
Slack calls its formatting mrkdwn, and the name is a warning: bold is one asterisk, italic is one underscore, and several things you expect are missing.
*bold*
_italic_
~strikethrough~
`inline code`
> a quote
- a bullet
1. a numbered item
```
a code block
```bold
italic
strikethrough
inline code
a quote
- a bullet
- a numbered item
a code block
What usually goes wrong
- One asterisk is bold, not italic. Two asterisks show as literal asterisks around bold text.
- One tilde strikes through; two show as text.
- No headings, no tables, no images, no task lists. Bold text is the usual stand-in for a heading.
- Links are
<https://example.com|the text>, not the square-and-round-bracket form.