What is meant by a static class?

In reply to dave_59:

Hi Dave ,

Could you please explain answer A3 above ?

" all static variables get initialized before time 0. "

We have 3 stages : Compilation , Elaboration and Simulation .

When exactly are the static Variables initialized ( Out of the above 3 Stages ) ?

A regression is run without re-compiling the design and testbench .
Just be changing Argument to +UVM_TESTNAME , the design can be re-simulated .

When does the factory registration take place ?
Can I say simulation is also divided into parts . One where Static Properties are Initialized and the other where simulation runs ?

Thanks in advance