"You can select any of the regression strategy to pick your test cases out of your suite, like..
1) Regress ALL - best(whole regression suite)
2) Regress severity and priority
3) Regress Defects/issues
4) Regress SMOKE suite
the above strategies are…"
Simply we make a decision about those test cases which we need to execute again and again... and test cases which covers that area of the application which may have side effects of the changes ... list those test cases…"