Northern Ireland

Although there are county pages for the 6 counties of the province of Ulster that became Northern Ireland after 1921 i.e. Armagh, Antrim, (London)Derry, Down, Monaghan & Tyrone, here are some useful shortcuts to online resources available today for this part of Ireland too.
The General Register Office of Northern Ireland (GRONI)
This pay-per-view site is where you can search for Births (more than 100 years ago), Marriages (over 75 years ago) and Deaths (over 50 years ago) for the 6 northern counties. It is the only place you can see images of the post-1922 records. You can search for free to get an idea of the numbers of candidate records that might meet your criteria but you will need to register and buy credits in order to view them. You also have to search in ranges of 5 years at a time, which can get a bit tedious.
If you need to search for more recent records in any of these categories, you will have to do that in person by booking a place in their search room - see their website for details.
There is quite a nice simple Townlands Map feature tucked away at the bottom the main page that will help you find places that you may be unfamiliar with. Either search by name of keep zooming in on the map in the general area you are interested in and the townland boundaries and names will appear.
The General Register Office of Northern Ireland (GRONI)
This pay-per-view site is where you can search for Births (more than 100 years ago), Marriages (over 75 years ago) and Deaths (over 50 years ago) for the 6 northern counties. It is the only place you can see images of the post-1922 records. You can search for free to get an idea of the numbers of candidate records that might meet your criteria but you will need to register and buy credits in order to view them. You also have to search in ranges of 5 years at a time, which can get a bit tedious.
If you need to search for more recent records in any of these categories, you will have to do that in person by booking a place in their search room - see their website for details.
There is quite a nice simple Townlands Map feature tucked away at the bottom the main page that will help you find places that you may be unfamiliar with. Either search by name of keep zooming in on the map in the general area you are interested in and the townland boundaries and names will appear.

The Public Record Office of Northern Ireland (PRONI) in the Titanic Quarter of Belfast should probably be your first port of call if you are planning a visit and you can find out more about what is on offer there on my page for this institution.
Placenames Northern Ireland - this is quite an academic website focusing on how language and history have particularly shaped the landscape of Northern Ireland's land units. There is a nice simple search facility and active map to zoom in on that also shows baronies within counties, parishes within baronies and townlands within parishes. There are also lists of different historical forms of place names in chronological order, many of which are in the Irish language. This should prove particularly useful on trying to resolve various different spellings of the same place that you might come across and have to account for when searching.

Another good resource for researching in of all the 9 counties of the ancient province of Ulster, is the North of Ireland Family History Society. They run an extensive branch network and have a research centre in Newtownabbey, Co. Antrim. Check out their website for the projects and resources that their members have got involved with and created to share. They also offer a look-up service for members who cannot visit in person which could be worth the membership alone. The society often exhibits at genealogy fairs and with Northern Irish ancestors myself, I've had several informative chats with some of their members over the years that have helped me with new ideas for research.

The Ulster Historical Foundation is another family history society covering the province. They have a very active programme of classes, services, talks and lecture tours, including a major USA tour most years. They also host quite a few transcribed online resources but most are only fully accessible to members. They offer both subscription and pay-per-view options for accessing content, although be sure to read the rules very carefully as it looks like members still have to buy credits to look at some records? If you can't make it to Northern Ireland easily yourself, then do an open query of the surnames that interest you and check out the Members Interests results - you might just find a new "best friend" with whom to share research with if you join.

The Linen Hall Library comes highly recommended by a fellow genie who has visited this veritable institution and availed herself of the genealogical resources on offer. There are a few digitised collections online, one of which is Postcards Ireland, through which you can buy reproductions of old images.
(c) Irish Geneaography - 2021