Excerpt from https://support.reddithelp.com/hc/en-us/articles/205926439-Reddiquette

Please do not:

• Be (intentionally) rude at all. ...

• Conduct personal attacks on other commenters. Ad hominem and other distracting attacks do not add anything to the conversation.

• Start a flame war. Just report and "walk away". If you really feel you have to confront them, leave a polite message with a quote or link to the rules, and no more.

• Insult others. Insults do not contribute to a rational discussion. Constructive Criticism, however, is appropriate and -encouraged.

• Troll. Trolling does not contribute to the conversation.Reddiquette is an informal expression of the values of many redditors, as written by redditors themselves.

• This sub does not tolerate obnoxious behavior. If you see breaches of the above in this sub, please use the Report button. The moderation team is active and will permanently remove individuals who have demonstrated incapacity for civil discussion