From about the 1840s the rise of literacy meant that the number of newspaper obituaries and marriage announcements rose sharply. In addition, the number of publications mushroomed as public opinion, and the press as the voice of public opinion, became more politically and socially important. As literacy grew, and as newspaper circulation expanded from the late nineteenth century into the early twentieth, this broadening of the social classes continued. Then, as now, publishing long lists of individuals--amateur football teams, successful candidates in the Intermediate Certificate examination, complete memberships of dramatic societies--was a way of ensuring that everyone on the list would buy the paper. With the advent of mass digitisation combined with full-text searching, all these lists are now potential genealogical sources.
From the late 1930s the newspaper death notice became an compulsory part of every Irish funeral, often recording age, extended family and place of death. The online availability of complete runs of all three national dailies - the Irish Press and Irish Independent at www.irishnewsarchive.com, the Irish Times at irishtimes.com/archive - has made these death notices a very significant element in any search for living relatives in Ireland.
The two main online archives, www.irishnewsarchive.com and www.britishnewspaperarchives.co.uk, have different strengths for post 1828 publications. INA is a clear leader for eighteenth century and twentieth century national and provincial newspapers. From 1840 or so, BNA has fuller runs of the provincial newspapers and is the only real source for nineteenth-century Ulster. Ideally both sites should be used - even where they cover what appears to be the same material, their OCR will have made different errors. They both offer short-term subscriptions, with BNA also allowing pay-per-view.
The BNA Irish material is also available for more restrictive searching on FindMyPast.ie. The counties section at johngrenham.com/browse gives details by county of all dates covered by these and any other online newspaper sites.