what doi need
Only if you are flying.
If you fly, the airline will request some form of ID. Currently the ferry companies don't require ID. There is no legal requirement for passports between the ROI and the UK.
no
Yeah you should have an id with you, it is very rarely chance that if someone ask you for your id... better to have
It depends where from.
With any air travel photo ID is required for all passengers, if in doubt contact your flight provider
Yes. A passport is not necessary to travel between Ireland and Britain.
In theory, no. There has always been unrestricted travel between the Republic of Ireland and the United Kingdom (which includes England). However, because of increased security levels in recent years, an acceptable photo ID is required before anyone can board a flight and a valid passport is the most acceptable form of ID.
I didn't need any ID when I went to the Isle of Man from Liverpool last year. (Please note capital letters.)
You need photographic ID for ANY flight!
well you need an ID to go there.
ID is very good - passports are not required
Theoretically no as Northern Ireland is part of the United Kingdom. However, acceptable photo ID is required to board an aircraft so if your journey involves flying, you will need ID and a passport is the most acceptable form of ID.