Infractions are the lowest level offense and are commonly traffic violations. Infractions are punishable by a fine only; no jail time and no probation. Unless the law states otherwise, infractions have a maximum fine of $250. A person does not have a right to have a jury trial or an attorney when charged with an infraction; this is because the consequence is so minimal. If you plea to an infraction, it will not be reported to the Department of Justice, which means that it will not show up in a common background check. The most common infractions are speeding and making an unsafe left or U-turn.
There are some offenses that can be charged as an infraction or a misdemeanor, like disturbing the peace, P.C. § 415 and exhibition of speed, V.C. § 23109(c). A misdemeanor is more serious than an infraction and in some situations may have detrimental consequences on your planned career path. (see How will my criminal history affect a future career in law enforcement?)