In its early days, the internet was mostly filled with IT people who communicated in forums and on mailing lists. It was clear to them how the internet works and which information can be read by whom. For example, it was obvious to them that emails are just as public as a postcard.
Once the internet started being used by ever more people outside of the IT scene, it could no longer be taken for granted that everyone shared the same pool of knowledge. So how does one communicate online, not just regarding the technology, but also regarding content? Netiquette arose to give laypeople some guidelines for their behavior.
In its early years, netiquette comprised not only the collection of rules for behavior but also information on data security and data protection. One of the older netiquette documents is RFC 1855, which contained tips on discussion culture in online forums as well as information on how to handle copyrighted content and chain emails.
Today the concept of netiquette has developed beyond its roots. Many basic elements from the 1990s still apply today and are in use by online communities. However, in recent years the focus has rested more on polite communication and less on technical aspects.