Two of the most difficult things that will confront a person who was convicted of a crime (or even someone who is not convicted, but was arrested for an alleged crime) are finding a place to live and obtaining a job. People who have a criminal history often have their past come back to haunt them, even after they have paid their debt to society (may it be jail time, or fines, or other consequences).
For example, people who are accused of sex crimes almost always get placed on a sex offender list. Being on this list comes with serious restrictions, such as not being able to live in certain areas (like near schools or parks).
Another example: people with a criminal history have to disclose that history when they apply for jobs. Though no company will admit it, that disclosure could play a role in rejecting the applicant for a position.
The major retailer Target, to its credit, is trying to step away from this potential bias. Target recently announced that they will no longer have a "check box" on their job applications that indicates if the applicant has a criminal history. The rule will apply only in Minnesota for the time being (in accordance with state law), but it will extend the practice to a national level in the coming months.
While this is a great step for Target, there are plenty of other companies out there who do not share this practice. Thus, plenty of people with a criminal history will struggle when applying for jobs. These people do have an option that could help them out: a criminal expungement. This process scrubs a person's criminal history and gives them the ability to leave that check box clear on a job application.
Source: MPR, "At Target, criminal history check box ends for job applicants," Rupa Shenoy, Oct. 25, 2013