What is the goal of fasting?

The ultimate goal of fasting is to develop Taqwa (consciousness of God) in humans, as Allah said,

“...so that it may produce Taqwa in you.”[1]

Taqwa is among the highest moral qualities that a Muslim can attain.  Taqwa comes from the verb “waqaa” which means “to defend”. Therefore, taqwa is produced by placing a shield between one's self and Allah's wrath. This is achieved by being conscious of Allah and obeying His commandments at all times, i.e., avoiding the Haram (prohibited) as well as the Makrooh (undesirable) and even some of the Halal (permissible) wherever doubt arises.

Reference:

[1] [Qur’an 2:183]