Arkan of Salat

 There are 14 Arkan of Salat. These 14 pillars must be done for the salat to be accepted.

1. Qiyam ma'il Qudrah fil fard (Standing, if able)
2. Takbeerat ul-ihram (Opening Takbir)
3. Qir`aat al-Fatihah (Recitation of Surat al-Fatihah)
4. Ruku` (Bowing)
5. Rafi' min ar-ruku' (Standing from bowing position)
6. Sujud 'alal a'dha a-sab'a (Prostrating on seven bones)
7. Al-i'tidhan min a sujud (Rising from sujud)
8. Al-jalsa bayna as-sajdatain (The sitting between the two sajdas)
9. Abta ma anina fi jami' arkani salat (Tranquility in all the pillars of the salat)
10. At-tartib baynal arkana salat (the proper order of the pillars of the salat)
11. At-tashahud al-akheer (The final tashahud)
12. A-julus li tashahud al-akheer (The sitting of the final tashahud)
13. A salatu 'ala nabiyan, salallaahu 'alaihi wa sallam (Sending salam upon the Prophet, salallaahu 'alaihi wa sallam)
14. 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.