What is obscenity How is it legally defined What are some of the important statutes and cases that impact obscenitypornography

What is obscenity? How is it legally defined? What are some of the important statutes and cases that impact obscenity/pornography?
Should Internet Service Providers (ISPs) be held criminally liable
for websites that depict child pornography on their servers? Provide at least one reason that supports criminal prosecution and one reason why the ISPs should not be held accountable for others who build these types of websites on the ISP servers.