When does the Tarawih prayer begin: on the eve of the first day of Ramadan, or after the 'Isha prayer on the first day of Ramadan?

Tarawih prayer is prescribed after the 'Isha prayer from the first night of Ramadan (definition) and ceases with the end of the month, either by sighting the crescent moon of Shawwal or by completing the counting [of 30 days]. It is specific to the month of Ramadan and is not related to daytime fasting. Its purpose is to attain the virtue of night vigil (qiyam (definition)) during it. Performing it in congregation is recommended and prescribed every night in Ramadan, whereas outside Ramadan, it is considered an innovation (bid'ah) if performed regularly in congregation in mosques. However, performing night vigil prayer (qiyam al-layl) in congregation occasionally at home is permissible, as was done by the Prophet, peace and blessings be upon him. Whoever prays it before the confirmed entry of Ramadan is like one who prays a prayer outside its prescribed time and will receive no reward.