Summarize this article in one sentence.
The police can arrest someone during a traffic stop when: the police officer personally saw the person commit a crime or the police officer has probable cause to arrest. When a police officer has a “reasonable belief, based on facts and circumstances, that a person has committed or is about to commit a crime, the officer may arrest that person.”  For example, if you're driving a car erratically and breaking traffic laws, the police officer may administer a breathalyzer test. If he determines that you have been drinking, the officer may arrest you. Or if the officer sees drugs in your car when he pulls you over, he will have probable cause to arrest you. Confirm that you are being arrested. Ask them if you are free to go. If they say no, then ask them what you are being arrested for. After this, you want to stop talking. If you are arrested, the police can do the following things simply because they have arrested you:  Search your body and clothing. Search your belongings. Search your vehicle if you were in it at the time they stopped you. Ask you to perform a test, such as a field sobriety test. Ask you questions. Note that you do not have to answer and you have the right to remain silent. If this happens to you, stay calm and cooperate with the police officer the best you can. Police are required to read you what are known as your “Miranda rights” before they question you after an arrest. This informs you of your right to remain silent when you are being questioned, if not anything you say “can and will be used against you.” The police cannot threaten you or force you in any other way to talk to them or give them any sort of statement. If this happens to you, tell your attorney immediately.  If the police start to ask you a lot of questions and you believe that you will be arrested (you will probably have a pretty good idea), it is best to stop talking. If you are going to be arrested - zip it. Anything you say before you have been arrested can be used against you. If police interrogate you without giving you the Miranda warning, the statements you make cannot be used as evidence against you at trial. Be aware that the police will ask you over and over again if you would like to talk to them even after you have been Mirandized. The police are allowed to trick you into talking. They are not required to be honest with you even after you have been Mirandized.

Summary:
Know when you can be arrested. Know what the police are permitted to do during and after an arrest. Understand your rights.