I haven't really noticed this before, but it seems there's some fad where a headline on a web page would include a mouse over paragraph marker (¶) that links to a named anchor for the headline. If you didn't catch that, here's a picture from three completely unrelated sites that all do the same thing:
URLs for each above are as follows, respectively:
http://docs.mathjax.org/en/latest/#basic-usage
http://docs.python.org/2/tutorial/controlflow.html#the-range-function
http://ruby-doc.org/core-2.0/Array.html#label-Creating+Arrays
I'm sure there's many more sites out there doing this. These were just the first three I encountered.
So,
Why is everyone using this? For example, did all of these web developers come to the same conclusion that this would improve the user experience?
Where did this style originate from (specifically the paragraph marker hover over effect)?
UPDATE:
All the given answers seem to miss what I was asking, they are all talking about the concept "Permalink". What I was trying to ask is how the hover over the title paragraph symbol became synonymous with "Permalink"?
As I think more on this, I believe the answer may have something to do with all these web-sites sharing the same underlying engine which arbitrarily chose the paragraph symbol in their styling of the permalink.