There are three types of criminal offenses in Pennsylvania - homicide, felony, and misdemeanor. In addition to criminal offenses, there is also something called a summary offense. Issues like underage drinking, obstruction of the highway, and my personal favorite - giving away a pig as a lottery prize - are all summary offenses. Usually, summaries are punishable by a fine. However, it is possible for many summaries to receive up to 90 days in jail.
If you have a clean record prior to being issued a citation for a summary offense, then you can almost certainly keep your record clean by arranging to do some community service or taking a class in anger management, for example. Hiring an attorney is very often not strictly necessary, but I always say better safe than sorry. Since summary offenses are not criminal offenses, you do not have the right to an attorney. If you cannot afford one, you are out of luck.