Hi! Thanks for the question!
When someone commits a crime and a report is given to the police station, it is known as the FIR(First Information Report). The initial information that police is given about a crime. It is the beginning of a case and investigation by the police.
Chargesheet is the end of the investigation. The police after investigating the case ie - Pieces of evidence and witnesses, prepare a report with detailed offenses that can be equaled against the accused. After this, the trial initiates in the court on the basis of charge sheet.
Remand is the process of detaining a person who has been arrested and charged with a criminal offense until their trial. Remand orders are given by the court in favor of the prosecution when they want the accused to be in their custody for being investigated or even when the person is risky to be left in open until trial. the remand period mostly is 14 days maximum,however, the court may use inherent powers if otherwise needed.