Times of Salaat

There are 5 times of obligatory (Farz) Salaat:

1.Time of Fajr (Dawn Salaat):

It starts from true dawn daybreak, when a horizontal whiteness appears on the horizon until a little before sunrise.

2.Time of Zuhr (Noon Salaat):

Its starts when the sun passes its meridian (zenith after Zawwal) and ends when the shadow of an object doubles.

3.Time of Asr(Late afternoon Salaat): It starts when the shadow of an object doubles and ends at sunset. 

4.Time of Magrib (Sunset Salaat): Begins at sunset until all whiteness disappears from the horizon.(approximately 1 hr. 20 minutes after sunset)

5.Time of Isha and Witr(Evening and Witr Salaat):

Starts from when all redness disappears from the horizon until True Dawn (daybreak). The Witr cannot be read before Esha since the sequence is necessary to maintain.

One performing Haj can combine the Zuhr and Asr on the plain of Arafat during the time of Zuhr on condition that he is in Ihraam and the Jamaat is led by the Ameer of Haj.

The Haji should combine the Magrib and Esha at the time of Isha when in Muzdalifah. It is not permissible for the Haji to
perform the Magrib on route to Muzdalifah.

source:Taleem uden by Shaykh Mufti Afzial Hoseen Elias