There arc obligatory Salat for a Muslim to perform, one of which is the five daily prayers. These arc obligatory on those who have become baligh. For the purpose of fulfillment of religious obligations, a boy becomes baligh after completing 15 years and a girl on the completion of 9 years (or earlier - for a detailed explanation, look at the books of Islamic laws).
source : http://www.maaref-foundation.com/
