Imsâk time: It is the end of Shar’î (canonical) night in all four madhhabs. It is the time when the whiteness called fajr sâdiq is seen at one of the points on the line of apparent horizon (ufq-i-zâhirî) in the east. This time is also the beginning of fast.

Sunrise: The time of morning prayer ends at the end of solar night, which is when the preceding [upper] limb of the Sun is observed to rise from the line of apparent horizon.

Ishrâq time: It is the time when the following (lower) limb of the Sun is as high as the length of a spear from the line of the apparent horizon, which corresponds to an altitude where its center is 5° above true horizon. It is the end of the karâhat time when the sun is rising.

Time of Dhahwa-i-kubrâ: Dhahwa-i-kubrâ time is the last time to make intention for fasting. Dhahwa-i-kubrâ time is the half time of the fasting period, that is Shar’î (canonical) day time, which is before zawâl time. Shar’î day is the time between imsâk time and maghrib time. That is, dhahwa-i-kubrâ time is half of the time between imsâk and maghrib. It is fard to make intention for Ramadan fasting by heart in the time from the sunset one day before till the Dhahwa-i-kubrâ time of the fasting day. It is the same for adaq fasting set for certain days and for nafila (supererogatory) fasting. But intention is not sahih after fajr (the time of imsâk) for the fasting of qadâ, kaffarat and adaq which is not set for certain days.

Time of zawwal karâhat: It is the time when when the Sun is within the celestial circle that circumscribes the region termed the shar'î (Islamic) zawâl. In other words, it is the period of time between the time a period of Tamkin prior to true culmination and the time another periof of Tamkin after it. So, it is equal to twice the amount of Tamkin for that city. This period of time is twenty (20) minutes in Istanbul. It is time when performing salat is makruh tahrimî, that is, harâm.

Time of zuhr: It starts when shortened shadows start to lengthen. The shar’î time of zuhr continues until the ’asr awwal, which is the time when the shadow of every thing longer than its shadow at the time of true zawâl by as much as its height, or until ’asr thânî, which is the time when its shadow’s length increases by twice its height. The former is according to the Two Imâms [Imâm Abû Yûsuf and Imâm Muhammad], and also according to the other three Madhhabs, and the latter is according to al-Imâm al-a’zam.

Time of asr prayer: Asr is also called asr-i awwal. It is the time when asr-i awwal starts according to the Two Imâms [Imâm Abû Yûsuf and Imâm Muhammad]. It is the same in the other three Madhhabs, too. It is the time when the shadow of everything becomes longer than its shadow at the time of true zawâl by as much as its height.

Time of asr-i thânî: It means the beginning of asr prayer according to al-Imâm al-a’zam. It is the time when the length of the shadow of everything increases by twice its height.

Karahat (isfirâr-i shams) time of asr: It is the time when performing salat is makrûh tahrimî, that is, harâm, during the Sun is setting. It starts after the Sun turns yellow, an event that takes place when the distance between the Sun’s lower [preceding] limb and the line of apparent horizon is a spear’s length, which is five angular degrees. The period of sunset begins when, in a dust free, smogless, clear sky, the places where sunlight is reflected on, or the Sun itself, become yellow enough to be looked at, and ends as it sinks (below the horizon). This time is called Isfirâr-i shams. Those who have not performed the asr prayer have to perform only the fard of it [even] at this time but should never leave it to qadâ.

Time of maghrib prayer: It begins when the Sun disappears and continues till the shafaq (evening twilight) gets darkened, that is, till the redness disappears.

Time of karahat (ishtibâk-i nujûm) of Maghrib: It is the time when the number of visible stars increase, or, in other words, after the following limb of the Sun has sunk down to an altitude of 10° below the line of apparent horizon. The period between this time and the time of sunset varies between 53 and 67 minutes in cities like Istanbul of which latitude is 41° in a year. It is sunnat to perform the maghrib prayer in the early time of its period. It is harâm to postpone it after Ishtibâk-i nujûm, that is, after the following limb of the Sun is sunk down to an altitude of 10° below the line of apparent horizon. For reasons such as illness, long-distance journeys, or in order to eat food that is ready, it might be postponed until that time.

Time of ishâ prayer: Ishâ-i-awwal is the first time of ishâ prayer. It is the time when the redness on the line of apparent horizon in the west disappears. That is, it is the time when the upper (following) limb of the Sun descends to an altitude of 17° below the surface horizon. The time of ishâ prayer starts at the ishâ-i-awwal according to the Two Imâms [Imâm Abû Yûsuf and Imâm Muhammad]. It is the same in other three Madhhabs, too.

The time of ishâ-i thâni: It starts after the whiteness on the line of apparent horizon in the west disappears. That is, the upper lib of the Sun on the line of apparent horizon descends to an altitude of 19° and the whiteness disappears. It is the ishâ prayer time according to al-Imâm al-a’zam.

Time of midnight (1/2 night): Shar’î night is the time from sunset till the fajr. That is, it is the time between the sunset, which is the time for salat-i maghrib, till imsâk. If the time between these two are divided by two and added to the maghrib prayer time, or subtracted from the fajr prayer time, the midnight is found. According to some scholars in the Shâfi’î Madhhab, the latest (âkhir) time for night prayer is until the shar’î midnight. According to them, it is not permissible to postpone the performance of night prayer till after the shar’î midnight. And it is makrûh in the Hanafî Madhhab.

Time of tahajjud: It is the time after two thirds of the Shar’î night, that is, the total time starting from the sunset which is maghrib prayer time, till the imsâk time, passes. In other words, it is the last one third of the Shar’î night. Tahajjud prayer is performed before imsâk time. Tahajjud means to give up sleeping. It is more virtuous than one thousand-rakat prayer performed during daytime. Performing two rakats of qadâ salat, in its turn, is more virtuous than performing salat-i tahajjud.

Time of dhawn: It is the last one sixth of the time between sunset time, that is, maghrib prayer time, and imsâk time. It says in the explanation of Shir’at-ul-islâm, “It was declared in a hadith-i sherif, ‘The prayers made in the time of dhawn at night and after prayers are accepted’. It is sunnat to start prayers with hamd and thana (salawat), and to rub the two pulms over the face are sunnat.” One should seize the opportunity making istighfar, crying and begging to Allahu ta’alâ during this time.