The UK Government has introduced legislation that requires airlines to submit Advanced Passenger Information (API) on all flights to and from the UK.
Your airline is legally obliged to collect passenger information from all guests (including infants) who are travelling to, and in some cases from, those countries involved in your itinerary that require information, for electronic transmission to the relevant country's Customs and Immigration authorities prior to departure.
Your airline will only provide each country with the relevant information requested by them for law enforcement purposes, the contents of which will not be used for any type of marketing activity.
This varies depending on the country you're visiting but normally includes:
The easiest way is through the airline's "Manage My Booking" facility on their website, please see the relevant airline's link below which will take you directly to the airline's website.
Where possible please ensure you enter your details at least 72 hours prior to your departure date. You will need to enter in the lead name and the airline booking reference which can be found under your flight details on your holiday documentation. If you are flying with any airline not listed here you will be able to provide your details at check in.