For most people with a minor criminal record that conviction becomes not only a personal embarrassment, but frequently also an employment problem. Having a criminal record can make finding and keeping a job much more difficult. Having a record that shows that you broke the law, were accused of breaking the law, or were convicted of breaking the law, may also derail your plans to travel as border agents are very interested in anyone with a record.
That is why most people want to eliminate their criminal activities from their official background, if they can. That usually means requesting that the information be expunged, or record be sealed. Expungement means that the record is destroyed, and anyone looking up your name in the jurisdiction in which the record was generated should not be able to find any information regarding the expunged incident. Once an expungement petition is granted, in theory the court administrator where the record was originally generated should notify any other agencies to which the criminal record was sent, requesting that this information be removed from those databases as well. But in reality, such requests may or may not be made by the original keeper of the records, and the other agencies that received the criminal record information may or may not update their files, so information about the conviction(s) may still show up in other databases.
As to immigration consequences, before seeking to expunge a criminal record you should know this: USCIS and the federal immigration courts often require that you disclose whether you have ever been arrested or detained by a law enforcement officer, charged with a criminal offense, convicted, what the sentence was if convicted, and the sentence actually served. Immigration agencies require this information regardless of whether the record has been expunged. And they demand certified records of these events, or a statement from the relevant agency stating that no record is available. This especially comes up in applications for citizenship benefits, and in deportation proceedings, where the respondent usually must prove “good moral character.”
Once the record has been expunged there is no way for the record-keeping agency to issue a certified copy of that record. If you request a written statement that the record is no longer available due to expungement, the record-keeping agency may refuse this request… and then you have a big problem. Immigration authorities have already received some sort of notice, whether through required self-disclosure or background checks, of you having a criminal record, however you cannot prove what actually happened. If you find yourself in that position, you may have no choice but to seek to have your criminal record reopened, and that is a tedious and unpleasant process, best avoided if possible. That is why you should at least delay having your criminal record expunged until after you have obtained certified copies of the arrest, conviction, and sentence, as well as the sentence actually served.