California has two types of probation: formal and informal. The Penal Code uses the term "conditional sentence" for informal probation, but lawyers and judges most often refer to it as court probation or summary probation. The major difference between informal and formal probation is how the probationer is supervised.
Those on informal probation aren't formally supervised and don't have probation officers that they have to report to. Informal probationers report directly to the court, and they typically only need to do so when they:
Because informal probationers don't have probation officers looking over their shoulders, they're less likely to pick up a probation violation than those on formal probation.
Someone on formal probation is supervised by a probation officer. A formal probationer ordinarily must meet with the officer anywhere from once a week to once a month, depending on what the officer requires. Most probation officers will require more frequent meetings, at least initially, for "high risk" probationers—ordinarily, those convicted of serious crimes or with long criminal records.
Following several years of good behavior, some judges are willing to modify formal probation to informal probation.
In most infraction and misdemeanor cases where the judge orders probation, it will be informal. (In practice, most infraction cases result in only a fine; judges rarely order probation.) If the judge orders a drug-testing condition in a misdemeanor case, probation will typically be formal—that's so a probation officer can supervise the testing. Probation in felony cases will almost always be formal.