Do you have to pay for Google API?

Hey there, I've been exploring different ways to enhance my app's functionality, and I've come across Google APIs as a potential solution. But I'm a bit unclear on the financial aspect of it. So, my question is, do you have to pay for Google API usage? Are there any free tiers or usage limits before I need to start shelling out cash? It would be great if you could clarify this for me. Thanks in advance!