The mid-year estimates refer to the population on 30 June of the reference year and are published annually. They are the official set of population estimates for the UK and its constituent countries, the regions and counties of England, and local authorities and their equivalents. This publication relates to the first release of the mid-2014 estimates of the UK and the revised mid-2013 estimates (background note 2 refers). The UK mid-year estimates series brings together population estimates that are produced annually for England and Wales by the Office for National Statistics (ONS), for Scotland by National Records of Scotland (NRS) and for Northern Ireland by the Northern Ireland Statistics and Research Agency (NISRA). The timetables for population outputs are available for each country on their respective websites. The official 2014 mid-year estimates for the UK referred to in this bulletin, build on the mid-2013 estimates, which are updated to account for population change during the period between 1 July 2013 and 30 June 2014 to give the mid-2014 estimates. A combination of registration, survey and administrative data are used to estimate the different components of population change and as such there will be a level of uncertainty associated with the estimated population. Mid-year population estimates relate to the usually resident population. They account for long-term international migrants (people who change their country of usual residence for a period of 12 months or more) but do not account for short-term migrants (people who come to or leave the country for a period of less than 12 months). This approach is consistent with the standard UN definition for population estimates which is based upon the concept of usual residence and includes people who reside, or intend to reside, in the country for at least twelve months, whatever their nationality.