Under the Miranda Rule, if you are in police custody you must be informed of specific constitutional rights before interrogation begins. Those rights are as follows:
The right to remain silent
The right to have an attorney present during questioning
The right to have an attorney appointed if you are unable to afford one

Important to note is that Miranda rights do not have to be read until you are taken into custody. That means that you can be questioned by the police before being taken into custody, and anything you say at that point can be used against you later in court.