There are a huge variety of records available online. But there are a few things to keep in mind:
No one website has it all – you will need to hunt around
Not everything is online – see the Books & Archives section
Sometimes only the ‘index’ is online – that is a database of limited details and no images
Not all records survive – disinterest, carelessness and accidents means that records were not always kept.
Not all websites are available to everyone – some are only accessible to universities.
Mar 13, 2015 - findingaids.nationalarchives.ie - 49
Free Transcripts from the surviving materials relating to transportation to Australia from Ireland between 1791 and 1853. Images are not online. See the National Archives of Ireland's guide to their complete holdings of transportation records.Mar 13, 2015 - search.findmypast.ie - 41
Subscription These records cover 3,127,598 prisoners who spent time in Irish prisons between 1790 and 1924. The records include the name of the prisoners, and in some cases the names next of kin and victims.Mar 13, 2015 - search.findmypast.ie - 45
Subscription The Petty Sessions handled the bulk of lesser legal cases, both criminal and civil - crimes range from allowing a cow to stray on a neighbour's land to minor assault. There are 22 million surviving records for Ireland. These records will be added to on an annual basis as the 100 year redaction rule dictates.