http://en.wikipedia.org/wiki/Wikipedia:Administrators

Administrators, commonly known as admins and also called sysops (system operators), are Wikipedia editors who have access to technical features that help with maintenance. Wikipedia practice is to grant administrator status to anyone who has been an active and regular Wikipedia contributor for at least a few months, is familiar with and respects Wikipedia policy, and who has gained the trust of the community. They can protect and delete pages, block other editors, and undo these actions as well. These privileges are granted indefinitely, and are only removed on request or under circumstances involving high level intervention (see Administrator abuse below). Administrators undertake additional responsibilities on a voluntary basis, and they are not employees of the Wikimedia Foundation.

In the very early days of Wikipedia, all users functioned as administrators. Any user can behave in a way befitting an administrator (provided they do not falsely claim to be one), even if they have not been given the extra administrative functions. Administrators themselves should not develop into a special subgroup but should be a part of the community like anyone else; the tools they are granted are technical, and do not convey authority. Although standards for administrator appointment have risen over time, several administrators are created every week. (There are currently 1,307 admins.)

Because administrators are expected to be experienced members of the community, users seeking help will often turn to an administrator for advice and information. In general, administrators acting in this role are neutral; they do not have any direct involvement in the issues they are helping people with.