Arrest means apprehension of a person by legal authority resulting in deprivation of his liberty. For instance, when a policeman apprehends a pick pocket, he is arresting the pickpocket; but when a dacoit apprehends a person with a view to extract ransom, the dacoit is not arresting the person but wrongfully confining him. Arrest of a person might be necessary under the following circumstances –
As a preventive or precautionary measure.
For securing attendance of accused at trial
For obtaining correct name and address
For removing obstruction to police
For retaking a person escaped from custody
F.I.R. means First Information Report, made to police, about commission of a cognizable offence, In effect, it amounts to putting law in to motion by giving information relating to the commission of a cognizable offence to an officer in charge of a police station, (which shall be reduced into writing and read over to the informant) and shall be signed by the person giving such information. It is mandatory to give a copy of the first information report (as recorded by police) to the complainant or informant free of cost.
Any person who is victim of an offence or who is a witness to any such offence or who has knowledge about the commission of any such offence can lodge an F.I.R.