The Central Statistics Office is launching Census 2011 today.
Some 5,000 census enumerators will begin distributing Census 2011 forms tomorrow.
By law the forms must be filled out by everyone present in every dwelling on Sunday 10 April - this includes people who may be staying with friends or relatives, in a hotel, in a guesthouse or on board a vessel.
The census enumerators then return to every dwelling to collect the completed forms within two or three days.
The last census took place five years ago.
The census is important because gives a thorough picture of the social and living conditions of people in Ireland.
Among other uses, the information is essential to plan for the provision of health care, education, and social services.
According to the Constitution, census information is also used to determine how many TDs are required, and where the constituencies should be.
