Berlin Endgame
Ruy López
1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O Nxe4 5.d4 Nd6 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8
A famous variation leading to an early exchange of queens and strategic endgame play.
Fun fact: Vladimir Kramnik used the Berlin to take the 2000 world championship from Garry Kasparov, drawing four of the eight games in which Kasparov had White. Source
Practice this lineThe idea
After 4.O-O Nxe4 5.d4 Nd6 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8, the queens are gone after only eight moves. Black has the bishop pair but doubled c-pawns, and the king has lost the right to castle. White has a healthy kingside pawn majority with a pawn on e5.
It looks quiet, but both sides have real winning chances: White with the pawn majority, Black with the bishop pair.
Plans for White
Use the kingside pawn majority and the e5 pawn, which cramps Black. Typical moves are Nc3, h3, Rd1+ and Bg5 or Bf4. White wants to create a passed pawn on the kingside while Black's doubled c-pawns make it hard for Black to do the same on the queenside.
Plans for Black
Bring the king to safety on c8 or e8, often with ...h6 and ...Ke8 or ...Bd7 and ...Kc8, and use the bishop pair. Black's position is very hard to break down if the king and pieces find good squares.
Watch out for
For Black, the king. With the queens off it isn't in danger of mate, but if it stays on d8 in the way of the rooks, White's pieces gain time with checks on the d-file.
For White, simplifying into a pure pawn endgame. White's majority is an advantage, but with the right exchanges Black's bishops and king become very active. Keep the pieces you need to press.