There are 14 Arkan of Salat. These 14 pillars must be done for the salat to be accepted.
- Qiyam ma'il Qudrah fil fard (Standing, if able)
- Takbeerat ul-ihram (Opening Takbir)
- Qir`aat al-Fatihah (Recitation of Surat al-Fatihah)
- Ruku` (Bowing)
- Rafi' min ar-ruku' (Standing from bowing position)
- Sujud 'alal a'dha a-sab'a (Prostrating on seven bones)
- Al-i'tidhan min a sujud (Rising from sujud)
- Al-jalsa bayna as-sajdatain (The sitting between the two sajdas)
- Abta ma anina fi jami' arkani salat (Tranquility in all the pillars of the salat)
- At-tartib baynal arkana salat (the proper order of the pillars of the salat)
- At-tashahud al-akheer (The final tashahud)
- A-julus li tashahud al-akheer (The sitting of the final tashahud)
- A salatu 'ala nabiyan, salallaahu 'alaihi wa sallam (Sending salam upon the Prophet, salallaahu 'alaihi wa sallam)
- Taslimatan (The two Taslims)
Source: Conditions, Pillars, and Wajibat of the Salat, by Shaikh Taraheeb ad-Dosiri
These actions are based on the evidences from Qur'an and Sunnah. You can find them listed here for each action.
All Sunni madh-habs (Hanafi, Shafi'i, Maliki, Hanbali) at least contain all these 14 Arkan of Salat.