The term community service refers to any act that is performed for the benefit of the community at large. Acts can range from a one-time effort to collect canned goods for the local food pantry to a weekly commitment to serve meals to the homeless. People do not receive money for their services.

In many cases, community service is performed as part of a person's membership in a social organization. Boy Scouts or Girl Scouts may volunteer to read to the elderly residents at a local nursing home or collect toys to distribute to needy children in the community. Members of a church fellowship may take a weekend trip to help build houses for Habitat for Humanity.

A person does not have to be a member of an organization to participate in community service activities, however. Many people choose to volunteer as a way to meet other people with similar interests, much like how one might socialize at a sporting event. Volunteering can be a great way for old people to remain active in their community. Stay at home parents often use volunteer work to keep their professional skills sharp during their break from the workforce.

Community service is sometimes required by schools as a condition for high school graduation. In addition to enhancing a student's college application, studies have shown that teenagers who volunteer typically show improved performance in schoolwork. 

Community service may also be ordered as punishment for a crime. In the case of nonviolent offenders, such as people convicted of drunk driving, it may be ordered instead of jail time. Cleaning up trash, removing graffiti, planting trees, or building playground equipment are common tasks performed under this type of arrangement.

Edited from: http://www.wisegeek.com/what-are-the-different-types-of-community-service.htm