Emily Post published her first book of etiquette back in the 1920's. There have been 19 updates since then. The most recent update is by Emily's great grand children Lizzie and Daniel. They've added a few chapters and revised several others. Here's a quick glance at what the book says.
1. Today good etiquette is all about communication. Take extra care in the way you talk to people
2. Treat texting like regular conversation. It's rude to delay answering a text. Bad news should always be delivered with a phone call, not a text.
3. As far as social media is concerned. It's perfectly fine to ignore a friend request, unfriend someone and untag yourself from a photo. But you should always be respectful
4. On the subject of on line dating the updated guide says if you don't get a response after a second message move on. Also, when you do actually meet someone for the first time regular social rules should be followed. "Ghosting" is not recommended.
Source: The Daily News