"(O Prophet) They ask you about the new moons. Say, These are means for measuring time for people's affairs and for the Pilgrimage" (Holy Quran, Ch. 2 V. 190)

Islam has made use of both the lunar and solar system of measuring times. Where worship is to be performed in different parts of the day the solar system of reckoning time is used as in the five daily Prayers or for the beginning and breaking of the fast, and where worship is to be completed within a particular month or part thereof, the lunar system is used, as in the determination of the month or part thereof, the lunar system is used, as in the determination of the month of fasting or fixing the time of Hajj or other festivals.

Following are the names of months in Islamic Calendar
Muharram-ul-Haram, Safar, Rabi-ul-Awwal, Rabi-ul-Akhir (Rabi-al-Thani), Jamadi-ul-Awwal, Jamadi-ul-Akhir (Jamadi-al-Thani), Rajab, Sha'aban, Ramadhan, Shawwal, Dhul Qadah, Dhul Hijja