Guide
Sunnah and Nafl: The Voluntary Prayers Around the Five
The five daily prayers are obligatory, but the Prophet Muhammad (peace be upon him) also regularly prayed additional units before and after several of them. These fall into two broad groups: the Sunnah prayers he kept consistently, and the wider category of nafl (purely voluntary) prayers. Observing them is encouraged, not required, and they are prayed within the same time windows as the obligatory prayer they accompany.
The regular Sunnah (Rawatib)
The emphasised regular Sunnah prayers most commonly cited are: two units before Fajr; four before Dhuhr and two after; two after Maghrib; and two after Isha. The two before Fajr are the most stressed of all — the Prophet is reported never to have left them. Counts vary a little between the schools of law, so a Hanafi and a Shafi'i timetable of Sunnah units may differ slightly.
Nafl: open voluntary prayer
Nafl prayers are optional prayers offered at almost any time outside the discouraged windows. They can be prayed in twos and are a way to draw nearer to God beyond the obligations. Several have their own names and times, such as Duha in the forenoon and Tahajjud in the depth of night.
Witr closes the night
After Isha comes Witr, an odd-numbered prayer that seals the day's worship. It is strongly encouraged in every school (and considered obligatory in the Hanafi school), and its window runs from after Isha until true dawn.
Why they matter
The regular Sunnah prayers are described in the tradition as a way of making up any shortfall in the obligatory prayers, and of building a steady rhythm of worship through the day. Because they sit inside the existing prayer windows, a good timetable is all you need to place them correctly.