What is netiquette?

Netiquette is a code of conduct for communicating online. It's a portmanteau, or merging, of the words "net" (as in internet or network) and "etiquette." Generally speaking, having good manners online entails the following:
Be just as courteous online as you would be in person.
No cyberbullying or trolling.
Obey copyright laws. Don't steal the work of others, and don't try to pass it off as your own.
Don't go overboard with emoticons and emoji.
These are just the ground rules for solid netiquette. Just like regular, offline etiquette, netiquette is situational. For example, good manners for a formal dinner at a swanky restaurant are different than good manners in the stands at a hockey game. In the same vein, the particulars of netiquette vary across internet platforms, like email, message boards, social media, blogging, and simply surfing the web. It might be fine to use the abbreviation "u" for the word "you" in an Instagram caption, for instance, but you should probably avoid it in an email to a teacher or coworker.
https://www.dictionary.com/browse/netiquette