Muslims worship the same God worshipped by Prophets Noah, Abraham, Moses and Jesus. The word "Allah" is simply the Arabic word for Almighty God – an Arabic word of rich meaning, denoting the one and only God. Allah is also the same word that Arabic speaking Christians and Jews use to refer to God.

However, although Muslims, Jews and Christians believe in the same God (the Creator), their concepts regarding Him differ significantly. For example, Muslims reject the idea of God having any partners or being part of a 'trinity', and ascribe perfection only to God, the Almighty.

Source: islamicpamphlets.com