Why i can insert records into standart table?

Hi, experts.

I’ve created an z program and try to add values into mara table.

Why values are adding without ‘commit work’ statement?

Is it should work like that?

data : ls_line type mara.
ls_line-matnr = ‘0000-00000-00000’.
insert into mara VALUES ls_line.

 Does ‘commit work’ starts only updates parts or it should be here too?