I've stumbled upon this opening a few times, and I'm pretty sure it must be known, but I couldn't find the name of it in my book:
[FEN ""]
1. e4 e5
2. Nf3 Nc6
3. d4 ...
Is someone familiar with that opening? If this is a common opening, I'd appreciate if you could point me to its pros/cons.
I'm not a pro and still learning chess gradually. Is this an opening in which I should consider progressing?