What are the pillars of fasting?

Scholars have differed concerning the pillars of fasting: The Hanbalis and Hanafis hold that it has one pillar, which is abstaining from things that invalidate the fast, and intention is a condition. Whereas the Malikis and Shafi'is hold that intention is a pillar, thus fasting has two pillars: intention and abstaining from things that invalidate the fast. The Shafi'is added a third pillar, which is the fasting person. All have agreed that abandoning a pillar or a condition invalidates the act of worship.