Step 1: Meaning of FIR.
A First Information Report (FIR) is the information given to police about a cognizable offence.
Step 2: Relevant provision.
Section 154 CrPC mandates that the police must record such information in writing, read it over to the informant, and obtain their signature.
Step 3: Conclusion.
Thus, FIR is registered strictly under Section 154 CrPC.