Ruku


Rukūʿ can refer to either of two things in Islam:
In prayer, it refers to the bowing at the waist from standing on the completion of recitation of a portion of the Qur'an in Islamic formal prayers. There is a consensus on the obligatory nature of the rukūʿ. The position of rukūʿ is established by bending over till the hands are on the knees and remaining in that position until one attains a relaxed state while glorifying God thrice or more in odd number of times.
In Al-Ghazali's book Inner Dimensions of Islamic Worship, he wrote about the rukūʿ by saying:

Qur'anic subdivision

The term rukūʿ — roughly translated to "passage", "pericope" or "stanza" — is also used to denote a group of thematically related verses in the Quran. Longer chapters in the Qur'an are usually divided into several rukūʿs, so that the reciters could identify when to make ruku in Salah without breaking an ongoing topic in the Quranic text.
There are 558 rukūʿs in the Qur'an. In some books, 540 have been mentioned which is actually misunderstood by some people with total rukus of quran recited in Tarawih prayer. This subdivision is not part of original revelation but adopted later-on to facilitate completion of Quran on the 27th night of Ramadan if one ruku is recited in each rakat of taraweeh prayers.