Online is used with these nouns:
ad, advertisement, alias, archive, arena, article, auction, banking, booking, business, catalogue, chat, commerce, communication, community, consumer, content, course, database, destination, diary, dictionary, direction, directory, discussion, donation, edition, editor, education, encyclopedia, environment, equivalent, exhibit, exhibition, form, forum, friend, gallery, gambling, game, guide, help, journal, journalism, learning, library, magazine, manual, map, marketing, marketplace, module, music, news, newspaper, petition, pharmacy, poll, posting, presence, programme, promotion, publication, publisher, publishing, purchase, questionnaire, quiz, résumé, reference, registration, reporter, reservation, resource, retailer, romance, sale, search, seminar, service, shopper, shopping, site, stockbroker, store, submission, subscription, supplement, survey, syllabus, system, tool, trading, transaction, translator, tutor, tutorial, update, version, video, viewer

Online is used with these verbs:
book, buy, chat, conduct, market, meet, order, publish, purchase, register, search, sign, submit, trade, visit, vote