I thought that IP checking and cookie writing and then reading were the only 2 ways
for a server to keep track of a user, but apparently there is another way.
What is that?

For example, this site is able to know who I am, even though I have cleared my
Cookies and use a different IP than the original IP I used to visit it 1st.
How is that possible?
How can a site keep track of you beside IP tracking and Cookie writhing / reading?

This issue/question has really been baffling me.