This is my first time that I'm studing a chess opening.
At first I thought I would have to know around 8 moves in a straight line, but after I started gathering information I was proven to be wrong. There are thousands of variations for every opening.
In this article I'll talk about the scotish gambit:
The main idea from any gambit is to get a better development than the oponent, at the price of some material.
At this point black have some possible moves like:
4. ... Bc5, with the idea to protect the pawn in d4
4. ... Nf6, giving up from the d4 pawn.
I'll try to focus on the first 8 moves.
 If Black plays 4. ... Bc,5 white have 2 main choices:
5. Ng5 - in this line white's attacks strongly, but if black defends well, they'll get a better game after the attack;
5. c3 - this line is recommended;
Against this line, black usually play one of the following moves:
5. ... Nf6 (transposes to a line of the Guioco Piano):
5. ... d3 (This move stops White building a pawn center with cxd4 and hinders the knight on b1):
5. ... Qe7?
More Variants :
Else If black response to 4. Bc4 with 4. Nf6:
 Here are other variations for the 4. Nf6:
Here's a match involving a scotch gambit:
In my point of view white will have to battle to develop his queenside
leziate and meniscuz for giving extra information about the opening