probation, method by which the punishment of a convicted offender is conditionally suspended. The offender must remain in the community and under the supervision of a probation officer, who is usually a court-appointed official. In theory, probation is not a form of leniency but is intended for offenders whose rehabilitation can be better achieved by community care than by imprisonment. However, the offender's original sentence remains in force and can be invoked should he violate the provisions of the probation. Probation differs from parole in that the latter requires the offender to have served a portion of his sentence in an institution. The first law in the United States that established the essentials of a modern probation system was enacted in Massachusetts in 1878; in 2000 some 4 million people were on probation in the United States.