Different things infuriate different people: whatever makes you angry, mad, or ticked off infuriates you.
Fury is a word for "anger" that should help with this word: to infuriate is to fill someone with fury, i.e., anger. Unless you're new to the planet, you've probably noticed many things that are infuriating: people talking too loudly on their phones, the cancellation of your favorite TV show, stepping in a puddle, someone stealing from you, stubbing your toe. These annoying events could infuriate anyone. Sometimes you might infuriate someone else by accident. Like it or not, we all infuriate someone sometime.