merge - when commits of both branch need to preserve - when additional zero file “merged commit” is ok - when chronology order of commits need to maintain r

merge - when commits of both branch need to preserve - when additional zero file “merged commit” is ok - when chronology order of commits need to maintain rebase - when commit of both need to preserve - when zero file “merged commit” is not desired - when rebased branch commits need to stay on top of other branch - when change of commit id is ok