Question Summary:
What are usool and furoo’?

Question Detail:

Can you please tell me in detail what are Usool and Furoo in usool al fiqh?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
 
Usools are principles used to derive laws from the Quran and hadith. Furoo’ are the laws that have been derived using these usools.
The topic of usool and furoo’ are generally taught in the third year of the aalim course. After one learns Arabic and a few traditional books of fiqh containing furoo’aat. These studies serve as a preliminary course to understand the intense studies of usools.
We advise you to enrol yourself for an aalim course to build your understanding to a point to be able to understand such intricate discussions. 
 
And Allah Ta’āla Knows Best
Muhammad Haris Siddiqui
Student Darul Iftaa
Melbourne, Australia  
Checked and Approved by,
Mufti Ebrahim Desai.