When composing a message, you'll start with plain and untouched text.
While plain text might work for simple communication, Slack apps tend to communicate complex data that benefits from more formatting.
It's beneficial to introduce as much structure and form to your message as possible. Formatting gives content a visual hierarchy that makes it easier to read.
Read our reference guide to formatting text for app surfaces to learn about the mrkdwn formatting syntax available for use in messages, modals, and Home tabs.