A misdemeanor is a crime which the courts can punish with up to one year in the County Jail and a fine of up to $1000. In practice, where jail is not imposed, courts will impose what is known as "summary probation" or "informal probation," where you agree to obey all laws and follow any other applicable terms and conditions. For example, a first or second offense DUI, petty theft and simple assault are examples of misdemeanors, although there are many, many others. Even if you do not serve a day in jail, a misdemeanor conviction alone can be very destructive. You will be saddled with a permanent criminal conviction on your record. If possible, it is best to avoid any conviction whatsoever, misdemeanor or otherwise. An experienced and skilled criminal defense attorney who knows the courts can help you avoid a conviction or help minimize it's consequences.