The f7 square is the weakest square on the board for black. It is the only square that is not defended by a major pieces or minor pieces. For this reason there are many traps to attack the f7 square
You should note that those players that start with e4 will usually get to attack the f7 square much more than those players that start with d4.
Here are some ways to attack the f7 square
The next one, from the Petroff Defense, is much more positional:
And here's a lesser-known but still very interesting variation from the Alekhine Defence:
Here's the start of a game played recently at the super-GM tournament in Dortmund: