Most toilets manufactured today are made of porcelain.
However some toilets were made of ceramic and some toilets are still ceramic but most toilets are made of porcelain and are easy to crack and break.
So you have to be very careful when installing a toilet or removing a toilet and when tightening the porcelain toilet down to the floor.
I once over tightened a bolt on a new toilet I was installing and it cracked it.
Luckily it was just my own toilet so I just left it as is.
You can also buy some toilets made of plastic but most will be made of ceramic or porcelain.