When you are charged with a crime, there is a maximum allowable sentence for that crime (i.e. jail, fine). A defense attorney will initially try to prove that you did not commit that crime. If proven guilty, a defense attorney will also try to prove that you are an upstanding member of society, and that you do not deserve the maximum allowable sentence. Based on the judge’s discretion, they may reduce your sentence, which can include probation. As long as you fulfill all the conditions of the probation you may avoid jail.