[zmmmmm]

> With copyright, if you fail to protect it adequately (which I don't think is very well defined by the court system), then the IP in question can pass into the public domain.

This is not true. Not even remotely true. It is routine that a company notices someone using their copyrights after decades and then sues about it. Oracle is suing Google over code that was "unprotected" for a decade before they decided to sue. In Australia (I know, different country, but this is the same), Men at Work were successfully sued 29 years after they released "Land Downunder" because it has a two bar riff with similarity to a song written in 1928 [1].

As a side note, I see this all the time. What is it about this particular topic that people seem to (a) consistently confuse these things but more importantly (b) feel confident enough about ti to repeat the confused viewpoint with certainty to others?

You are probably thinking of trademarks.

[1] https://en.wikipedia.org/wiki/Down_Under_(song)