There are five prayers obligatory for a Muslim, five times a day. Holy Prophet Muhammad S.A.W. taught us the method to offer our prayers. In Salah some are obligatory acts, the omission of which results in repeating salah and some are wajib which if one forgets, will not break the salah but to rectify the prayer it is obligatory to perform an extra prostration i.e. forgetfulness prostration or sajda sahw. There are in total 14 fard parts of the daily prayer or Salah. There are 7 Fard pre-requisites of Salah and 7 fard acts during Salah. Following seven are the acts, if not performed in salah, the salah is invalidated and this is irrelevant whether the omission is intentional or by mistake. Even Sajda Sahw cannot compensate an omission in one of these fard. These are obligatory acts in prayer called Faraidh. It also does not matter whether you are a male or a female, you will need to repeat your prayers in the case of omission of these obligatory acts. The 7 faraidh in a salah are given below;[irp]
Takbeer Tahreema: It is the opening Takbeer to begin your Salah. Every Muslim who says prayer must say Allahu-Akbar by raising his hands to start the prayer. This shall be said in such way that at least the person himself can hear his voice, and if he forgets it, he has to repeat his prayer.
Qiyaam: In the case of physical illness or restriction you can sit and say a prayer but if you have no physical illness or restriction then it is obligatory for you to stand and pray. The period of standing is equivalent to the length of your recitation. Standing in Salah is described as being in a straight position so that if your arms are left freely hanging by your sides they will not be reaching your knees.
Recitation: It is called as Qiraa-at which means recitation of the Holy Quran. During reciting Quran one should utter or say every word clear and in a low pitch voice so he could hear his own voice because if he couldn’t, the salah is not valid
Ruku: It is also an obligatory act in prayer. Bowing your head and body in prayer is called ruku. There is a bit difference between man and woman’s way of Bowing. To an extent for men, the back should be so straight in level with the floor that if a bowl filled with water is placed on your back, the water does not flow over. However, for the women it is just enough that their hands reach the knees.
Sajo’od: The position in the prayer to bow down as to touch the floor with forehead is called Sajda or prostration. There are two prostrations in each Rakaah or unit of a prayer. You have to do both sajdahs together as it is one of the faraidh in Salah. These two prostrations are obligatory in each Rakaah. And if you forget or left out any sajdah deliberately or unintentionally then your prayer will become void. Keep this thing in mind that the posture for prostration is slightly different for male and female.[irp]
Qaa’dah Akheerah: It is an obligatory act of prayer. Qaa’dah Akheerah is the last sitting posture in prayer to recite Tashahudd. It is a fard to sit in the last rakaah of prayer so long that you could recite whole Tashahudd. It is also called Khurooj-e-Bisun'ihee which means to end the prayer with the intention that you have completed all the recitation.
Salam: You must be saying salam at the end of the prayer Assalam-o-Alaikum wa Rahmatullah, if not then you have to repeat your salah
Source: Central Mosque