"What does it mean when you “expunge” your criminal record?
It means, that, subject to certain exceptions, you are relieved of the legal disabilities resulting from the conviction. In many respects, it is as if the conviction never occurred. However, the record of the conviction does not disappear. Instead, it is augmented to reflect that it has been expunged.
However, law enforcement will still see it when they pull up your records, if they run your rap sheet. If it is the conviction in questions is an offense that carries extra punishment for repeat offenders, such as drunk driving or theft, even an expunged prior conviction will make your second arrest count as a “second offense.” Fire arm restrictions are not eliminated by expungement either. Many immigration lawyers recommend that their clients expunge their records as part of their representation in immigration cases. Please see California Penal Code Sections 1203.4 and 1203.4a for complete details. http://www.leginfo.ca.gov/calaw.html
If you have a conviction on your record, and you have fully completed the terms of probation, and you have no criminal cases now pending, you should petition for expungement. The court must grant the petition if you qualify, unless you have waited so long that the actual court file has been destroyed."