It is generally a complaint lodged with the police by the victim of a cognizable offence or by someone on his/her behalf. ... Anyone who knows about the commission of a cognizable offence can file an FIR. It is not necessary that only the victim of the crime should file an FIR.
Every information relating to the commission of a cognizable offence, if given orally to an officer in charge of a police station, shall be reduced to writing by him or under his direction, and be read Over to the informant; and every such information, whether given in writing or reduced to writing as aforesaid, shall be signed by the person giving it, and the substance thereof shall be entered in a book to be kept by such officer in such form as the State Government may prescribe in this behalf