Published in 2000, is one of the key works which explains the rise of social media. It made quite an impact on me when I first read it. You can read it for free here.
Here are six lessons which the Cluetrain Manifesto teaches in its 95 theses:
1 Markets are conversations
2 Markets consist of human beings, not demographic sectors
3 Conversations among human beings sound human. They are conducted in a human voice
4 Whether delivering information, opinions, perspectives, dissenting arguments, or humorous asides, the human voice is typically open, natural, uncontrived
5 People recognize each other as such from the sound of this voice.
6 The internet is enabling conversations among human beings that were simply not possible in the era of mass media