Witnesses are not limited to "eye witnesses." You may have seen or heard the crime happen or may know something about it. You may also know something about a piece of evidence, or may know something that contradicts another witness' testimony.
You may not think that what you know about the case is very significant; however, small pieces of information are often required to determine what really happened. If you wonder "why" you are testifying in a particular case, ask the Assistant Prosecutor handling it (or our Witness Coordinator); there is probably a common-sense reason.
Your presence and willingness to testify may be the deciding factor in determining what will be done in the case. Many defendants hope that you or other witnesses will not show up. Your mere presence at the courthouse before the trial may cause the defendant to plead guilty.