The term 'remand' basically implies the act of sending the accused back to custody either to provide security or to provide surety for bail. This can also be done when an appellate courts send back an accused to the trial court for further hearing.
Whenever a person is arrested, he is kept in custody for 24 hours to be produced before a magistrate. When the accused needs to be further retained for investigations, it is known as police custody but if the term expires in police custody and the accused needs to be kept under custody for further investigation or stoping witnesses from going hostile, the court orders the accused to be kept in jail and is known as judicial custody. This remand is as per Section 344 of the CRPC. Sometimes, a trial court could have committed a mistake and the appellate court orders fresh hearing or review of hearing at the trial court. In this case, the accused is again sent to judicial custody.
Depending on the profile of the person arrested, the treatment at jail varies with respect to facilities granted during their stay. A political person is given A class jail and better facilities than normal accused citizens. However, the method of investigation remains common for all. The investigating agency is allowed to retire facts through any methods suitable to the case.