These are some commonly used prefixes (courtesy of prefix.cc) that are redefined by a URI scheme of the same name.

Back to the scheme description.

PrefixNamespace
content:http://purl.org/rss/1.0/modules/content/
data:http://data.odw.tw/
example:http://www.example.org/rdf#
feed:https://www.feedipedia.org/
geo:http://www.opengis.net/ont/geosparql#
go:http://purl.org/obo/owl/GO#
http:http://www.w3.org/2011/http#
icon:https://w3id.org/icon/ontology/
im:http://imgpedia.dcc.uchile.cl/resource/
lastfm:http://purl.org/ontology/last-fm/
ldap:http://purl.org/net/ldap/
nih:http://ncicb.nci.nih.gov/xml/owl/EVS/Thesaurus.owl#
payment:http://reference.data.gov.uk/def/payment#
pop:http://wiki.dbpedia.org/
resource:http://dbpedia.org/resource/
service:http://purl.org/ontology/service#
session:http://redfoot.net/2005/session#
swid:http://semanticweb.org/id/
tag:http://www.holygoat.co.uk/owl/redwood/0.1/tags/
urn:http://fliqz.com/
ws:http://www.w3.org/ns/pim/space#