"In a criminal law context, bail is most often thought of as the posting of security to ensure the presence of an accused at subsequent judicial proceedings--that is, 'to obtain the release of (oneself or another) by providing security for future appearance.' The term itself is less frequently used now, however, due in part to the practice of release on personal recognizance, which consists of permitting an individual to pledge his word, rather than his property, for his future appearance. Moreover, today, an individual's release pending subsequent criminal proceedings is often predicated on conditions other than, or in addition to, the posting of an appearance bond, secured or unsecured. As a consequence, rather than speaking of bail, existing federal law refers to release or detention pending trial, to release or detention pending sentencing or appeal, and to release or detention of a material witness. This is an overview of federal law in each of these areas, as well as in the area of extradition from the United States to another country"
CRS Report for Congress, R40222
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html