A preliminary hearing is a very important event in the criminal justice system. It is not where the Commonwealth has to prove you guilty beyond a reasonable doubt, but where the Commonwealth must show a prima facie case. Prima facie means correct until proved other wise. Typically a defendant does not testify at a preliminary hearing because all of the Commonwealth’s evidence and testimony is considered true at this level. So if their is contradicting testimony, the Magistrate Judge is required to believe the testimony of the Commonwealth witnesses no matter how incredible.
If through testimony the Commonwealth sets out all of the elements of the crime charged and are able to point to the Defendant as the perpetrator of that crime, then the charges are bound over for court. That means the charges move on to the Court of Common Pleas, where you have the right to a trial and the burden shifts to the Commonwealth to prove the allegations beyond a reasonable doubt.