Query on the name "Martinez"

[Ittaob at AOL.COM]

In a message dated 10/8/01 8:32:22 PM, gcohen at UMR.EDU writes:

<< This is a bit off-topic, but maybe someone can help. The "-ez"
of Spanish surnames like "Martinez" supposedly means "son of," so
"Martinez" is "son of Martin," just as (for example) "Johnson" is
"son of John."

      But where did this "-ez" come from?  Would anyone know?
 >>

Is this true? Then Gomez means "son of Gom" and Lopez means "son of Lop"?
These don't sound like Spanish given names.

Steve Boatti