It is well-known and popular that there are five pillars of Islam. One of the proofs that these five things are pillars is the following hadith.

Narrated Ibn Umar:

The Messenger of Allah (peace be upon him) said: "Islam is based upon five: the testimony of La Ilaha Illallah, and that Muhammad is the Messenger of Allah, the establishment of the Salat, giving the Zakat, fasting (the month of) Ramadan, and performing Hajj to the House."

Since these things are the pillars of the Islamic building, we said that Islam is built on those five things. However, this does not mean that Islam consists of only five things. They are the foundation and the pillar. These five things are at the very core of Islam, just as each building has the cornerstone. To make the building perfect, you will need to build walls, pillars, and other works around the base. The same is true of the other fard and wajib of Islam.

It is clear from the hadith that man cannot be a Muslim without these five things. Everyone has agreed that anyone who denies any of them is an unbeliever. These five pillars are fard ayn, that is, individually and indirectly. It is fard for a person who claims to be a Muslim to perform these prayers personally.