worship

Allah, the Exalted, says:

"Verily I (alone) am Allah: there is no god but I: worship (only) Me and keep up prayer for My remembrance." Holy Qur'an (20:14)

As Islam ordains the basis of faith and how to deal with matters related to ideology, and how to consolidate psychological and moral principles in the depths of the human conscience, it also organizes the life of mankind and the relationship with the Creator.

Allah specifies certain acts of worship to be performed such as the daily five times a day prayer, fasting, Hajj (pilgramage), supplication, dedicating things by vow to Allah, reciting the Qur'an...etc. so that man can express his servitute and loyality to his Creator, and free himself from the shackles of lusts and Taghuts (false-deities.)

To be ritually clean from all such impurities as urine, faeces, blood, sperm carcasses, swine, dogs are preconditions for engaging in worship. For example, to perform prayers, one should do the ablution: However, Ghusl (obligatory bath) is required in certain cases such as after sexual intercourse and discharge of semen for men and for women after their monthy cycle, childbirth or sexual intercourse.

Every obligatory act has a purpose behind. The daily prayers are a constant reminder of the bond between the Creator and created and ensure virtue and uprightness.

The fasting of Ramadhan is a period of reflection over past deeds and self-reformation. It also builds up discipline, improves health by cutting off gluttony.

As for the Hajj pilgrimage to the Holy Ka'aba in Mecca, it is obligatory once in a lifetime for an adult and sane muslim provided he or she can afford the journey. It is the greatest annual assembly on earth and is a wonderful intermingling of different races, languages, colours, classes and customs in the harmonious melting-pot called Islam. The multi-sided Hajj is the finest expression of worship for the one and only Creator and a forum for discussing the issues of the Ummah.
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Ref: The Meaning of Islam
Al-Balagh Foundation