Why shouldn't data be modified on an HTTP GET request?

Question

I know that using non-GET methods (POST, PUT, DELETE) to modify server data is The Right Way to do things. I can find multiple resources claiming that GET requests should no

Answer 1

How about Google finding a link to that page with all the GET parameters in the URL and revisiting it every now and then? That could lead to a disaster.

There's a funny article about this on The Daily WTF.