It was written by Jamal Munshi of Sonoma State University He used engines to evaluate the effectiveness of gambits by comparing ten gambit continuations with their closest mainline non-gambit twin. Six of the gambits failed because they favored the opponent. If you are a math person, you might find the statistics interesting.
I can't tell the difference between the Danish and the Goring, but in the Danish Gambit (1. e4 e5 2. d4 exd4 3. c3) white sacrifices one or two Pawns for the sake of rapid development and, hopefully, an attack. The only problem is that if black is careful he can defend and keep the Pawns, or he can simply decline it which leads to rather boring (I think) play.
Danish player Martin Severin From essayed the gambit in Paris 1867 tournament and is usually given credit for popularizing it. The Danish Gambit was popular with attacking players like Alekhine, Marshall, Blackburne, and Mieses, but defensive lines for black were discovered and it lost favor. Frank Marshall once commented that he had to give it up because the players at his club were getting booked up and it no longer worked.
It's not for the faint of heart because many games are short...white either breaks through and mates early or if black defends well, white's game will either be in a shambles or he will have equality at best. If black accepts, white will have a strong pair of Bishops aimed at black's K-side, plus black will be behind in development. That's why it is often declined. It's important for white to hang on to the B-pair.
GM Boris Alterman's blog has some interesting analysis on the Danish:
I can't say that I recommend playing the Danish (or Goring) because even though white CAN get a very dangerous attack, it seems we amateurs lack the tactical prowess to take advantage of any mistakes black makes and the result is we may easily find ourselves down a P or two right out of the opening and no big-time attack like the books say...at least that's what happened to me.
Even Homer nods as we see in the following game by Nakamura.