Short answer
Salah is the Arabic word for the ritual prayer Muslims perform five times a day. Its root meaning is du'a (supplication) and connection. "Salat" is the same word in another spelling, and "namaz" is the Persian and Urdu word for it. It is the second pillar of Islam, after the shahada.
In the Sharia, salah is a set act of worship made of specific words and actions, opened with the takbir and closed with the salam. The five daily prayers are fard on every sane adult Muslim, and someone who denies that they are obligatory leaves Islam.
The four schools agree on this.
Explanation
In Arabic, salah (صلاة) originally means du'a, a call or supplication. In Islamic law it came to mean the specific prayer the Prophet ﷺ taught: standing, reciting the Quran, bowing, prostrating and sitting, from the opening "Allahu akbar" to the closing "as-salamu 'alaykum". The four schools agree on this definition.
- Salah or salat? Both. The word ends in a letter that is pronounced "t" when joined to the next word (salat al-fajr) and "h" or silent at a pause (salah).
- Namaz: the Persian word, used in Urdu, Turkish, Bengali and other languages.
- Solat: the common spelling in Malaysia and Indonesia.
- Du'a: personal supplication in any words and any language, at any time. Salah has a fixed form; du'a is part of it but also stands alone.
Salah is the second of the five pillars of Islam. Muslims pray five times a day: Fajr, Dhuhr, Asr, Maghrib and Isha. The Quran mentions it again and again alongside zakah, and describes it as something that keeps a person away from shameful deeds.
To learn it step by step, see how to pray. For why there are five, read why Muslims pray five times a day, and for the other prayers see all the prayers in Islam.
The evidence
Quran, Surah Al-Baqara 2:43
وَأَقِيمُوا۟ ٱلصَّلَوٰةَ وَءَاتُوا۟ ٱلزَّكَوٰةَ وَٱرْكَعُوا۟ مَعَ ٱلرَّٰكِعِينَ ﴿٤٣﴾
And establish prayer and give zakah and bow with those who bow [in worship and obedience].
Salah is commanded alongside zakah as a core duty.
Quran, Surah Al-Ankaboot 29:45
ٱتْلُ مَآ أُوحِىَ إِلَيْكَ مِنَ ٱلْكِتَٰبِ وَأَقِمِ ٱلصَّلَوٰةَ ۖ إِنَّ ٱلصَّلَوٰةَ تَنْهَىٰ عَنِ ٱلْفَحْشَآءِ وَٱلْمُنكَرِ ۗ وَلَذِكْرُ ٱللَّهِ أَكْبَرُ ۗ وَٱللَّهُ يَعْلَمُ مَا تَصْنَعُونَ ﴿٤٥﴾
Recite, [O Muhammad], what has been revealed to you of the Book and establish prayer. Indeed, prayer prohibits immorality and wrongdoing, and the remembrance of Allah is greater. And Allah knows that which you do.
Salah shapes a person's conduct.
Sahih al-Bukhari 8
Sahih... بني الإسلام على خمس ...
"Islam is built on five."
Salah is one of the five pillars, listed right after the shahada.
Where the ruling is recorded
- al-Durr al-Mukhtar with Radd al-Muhtar, Opening of Kitab al-Salah. Defines salah in language as du'a and in the Sharia as specific words and acts opened with takbir and closed with salam.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.