Classification of Fiqh

Fiqh can be categorised:

According to the evidences:

Adillatu Qat'iyyah: Those issues which are based on direct proof, where direct textual evidences exist in the Qur'aan and Sunnah. For example, the obligation of the 5 prayers is based on direct textual proofs.

Addillatu Dhanniyyah: Those issues which are based on indirect proofs, where juristic differences occur due to different interpretations of a textual evidence. For example, the amount that must be recited in a raka'ah is based on different indirect texts which result in different juristic opinions.

According to the topics:

Fiqh ul 'ibaadaat: The fiqh of acts of worship.

Fiqh ul mu'aamalaat: The fiqh of dealings/worldly issues.

Fiqh ul qaanun ad dawli: The fiqh of international affirs.

And many other categories/ways of categorising by topic.

According to the wisdoms behind:

Those issues where the wisdom behind a ruling is known and understood. For example, we know that the shaytaan causes hatred and animosity through gambling and wine as in [5:91]. Similarly, fasting makes one have taqwa as in [2:183].

Those issues where the wisdom behind the ruling is not known and/or understood. The scholars mentioned that these issues test whether a person is really a believer or not and are known as al ahkaam al 'uboodiyyah. For example, we do not know why we pray 4 raka'ah in some prayers and 3 or 2 in others. Similarly, we do not know the true reason why Allah has forbidden us from eating the meat of the pig.