:sl:
As the brother above said, there are different parts or actions in Salah and each of them have different category. Please see this post for details on the pre-requisites, the
arkaan (pillars),
waajibaat and
sunan of Salah:
Basics of Prayer
If you miss a pre-requisite or a
rukn (a pillar) of Salah, you will have to repeat your prayer completely. If you miss or forget a Wajib, then you have to make two extra prostrations of forgetfulness at the end. But if you involuntarily miss a Sunnah action of prayer, then you don't have to do anything, the prayer will be valid :ia:.