Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...d6

= Ruy Lopez = The move is sometimes called the Old Steinitz Defence because it is viewed as not best for black. The pawn on e5 is not threatened by Bxc6 so there is no need to defend it. Black allows his light square Bishop to become active, but at the same time his dark square bishop is getting blocked, so there isn't much of any gain in development. The move also allows white to play d4 immediately.

Theory table
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 * 1.e4 e5 2.Nf3 Nc6 3.Bb5 d6