The Five Pillars of Islam
The five pillars of Islam are the framework of obligatory practice that defines what it means, in a structural sense, to be Muslim — distinct from belief itself (which is centered on the six articles of faith) and focused instead on action. They are named together in a well-known hadith in which the Prophet ﷺ lists them directly: testimony of faith, prayer, zakat, fasting, and pilgrimage.
The first, shahada, is the testimony that there is no god but Allah and that Muhammad ﷺ is His messenger — a short declaration, but the one that formally marks entry into Islam, and the foundation the other four pillars build on. The second, salah, is the five daily prayers performed at their fixed times, described in the same hadith as the pillar most directly connecting a person to Allah on a daily, structured basis. The third, zakat, is obligatory almsgiving — a fixed portion (2.5% for most forms of wealth) of a Muslim's qualifying wealth given annually to those it's owed to, addressed in detail in this site's zakat guides.
The fourth pillar, sawm, is fasting during the month of Ramadan — abstaining from food, drink, and intimate relations from dawn to sunset for the entire month, one of the practices most associated with Islam even among people unfamiliar with the other pillars. The fifth, Hajj, is the pilgrimage to Mecca, obligatory once in a lifetime specifically for those who are financially and physically able to make the journey — a condition (istita'ah) that means Hajj, unlike the other four pillars, isn't equally binding on every Muslim at every point in their life.
It's worth noting these five are described as pillars — a structural metaphor, not a checklist to complete once. Four of the five (prayer, zakat, fasting, and the testimony of faith as an ongoing conviction rather than a one-time statement) are recurring, lifelong practices rather than single acts; only Hajj has a "once is enough" character to its obligation. For someone newer to learning about Islamic practice, this site's individual guides on prayer, wudu, fasting, and zakat go into the detail each pillar deserves beyond this overview.