How does one distinguish a "complement" from a "predicate"?

[zaba]

I guess these terms come from different traditions. What is the difference in the kind of thing to which they refer?

[Daniel]

A predicate is the "verby" part of a sentence. A "complement" is the main, usually required, argument for some element.

Predicate: I sing. / I see you.
Complement: I see you.