Is it mandatory to follow a specific madhhab (Hanafi, Shafi'i, etc.)?

A madhhab (plural: madhahib) is a school of Islamic jurisprudence — a systematic methodology for deriving legal rulings from the Quran and Sunnah. The four Sunni madhabs are: Hanafi (predominant in South/Central Asia and Turkey), Maliki (predominant in North/West Africa), Shafi'i (predominant in East Africa and Southeast Asia), and Hanbali (predominant in Saudi Arabia).

For qualified scholars (mujtahidun) who have deep knowledge of Arabic, the Quran, hadith sciences, and legal methodology, it is acceptable to derive rulings directly from the primary sources. However, the vast majority of Muslims are not at this level.

For the average Muslim (non-scholar), following one of the four recognized madhabs provides important benefits: consistency (your rulings are internally consistent rather than contradictory), accountability (you follow a complete, tested methodology), protection from nafs (following a madhhab prevents "fatwa shopping" — picking the easiest ruling on each issue from different schools).

What most scholars caution against is: talfiq (combining rulings from different madhabs in a way that produces a result no individual scholar or school would have permitted), following weak or obscure opinions purely to make worship easier, or dismissing scholars entirely. All four madhabs are valid, and a Muslim who moves from one to another for a legitimate reason is not doing anything wrong.