In Islam, Allah is the essential personal name of God and comprises all His Beautiful Names (the 99 Names of God). When Allah is said, the One, the Supreme Being, the Creator, the Owner, the Sustainer, the All-Powerful, the All-Knowing, the All-Encompassing, whose Names and Attributes are manifested in creation, comes to mind. This term also refers to His absolute Oneness as well as His having no internal defect or external partner. In Arabic, the name is composed of four letters, ا ل ل ه (or Alif Lam Lam Ha) which when brought together make الله. Arab Christians believe that Allah consists of the Father, Son and Spirit, that together constitutes complete Allah.
Christianity and Judaism
The word Allah is used by Arab Christians throughout the Middle East, it is also used by Arabic Jews mostly residing in Yemen.
Takbeer (Glorification of God)
Takbeer (تَكْبِير) (Glorification of God), is the common way Muslims give glory to God, the wording it self is Allahu-Akbar "الله أكبر" and translates to God is greater. It is a very common practice in Islam and is essential to the Islamic call of prayer (Athan).