What are the main differences between Audi's A3, A4, and A5 models?

I am new to the Audi brand and I am looking to purchase a new car. I am interested in the A3, A4, and A5 models but I am not sure which one would be the best fit for me. Can someone explain the key differences between these models and what I should consider when making my decision?

The A3, A4, and A5 all have different engine options. The A3 has a standard 2.0-liter turbocharged engine, while the A4 offers an optional V6 engine. The A5 has a standard 2.0-liter turbo engine but also offers a higher-performing S5 model with a V6 engine.

The A3 is Audi's entry-level compact sedan, while the A4 is a mid-size sedan. The A5 is a luxury sports coupe. When making your decision, consider your desired size, performance, and budget.