Chapter Two Population Size, Distribution and Characteristics By the end of 2021, it is estimated that 9.17 million of the 14 million Palestinians worldwide (65.5 percent) are forcibly displaced persons.201 Among them are approximately 8.36 million Palestinian refugees and 812,000 IDPs.202 Palestinians form the largest and most protracted population of refugees, and the second largest displaced population in the world, second only to Syrians.203 The Palestinian refugee and IDP population described here is based on the total estimated number of Palestinians and their descendants who have been and continue to be displaced from their homes and properties located in Mandatory Palestine due to fear of persecution and/or lack of protection. Palestinian refugees fall into three main categories: (1) those who were forced to flee their homes and country during the Nakba of 1947-1949 and their descendants (7.0 million), (2) those displaced during the 1967 War and their descendants (1.33 million), and (3) an unknown number of Palestinians who are neither 1948 nor 1967 refugees, but who have also been forcibly displaced outside the area of Mandatory Palestine and are unable or unwilling to return to their homes owing to a well-founded fear of persecution for reasons of race, religion, nationality, membership of a particular social group, or political opinion. As for Palestinian IDPs, they include two main categories: (1) Palestinians who have been internally displaced and remained inside what became Israel since 1948 and their descendants (439,171) and (2) Palestinians who have been internally displaced in the oPt since 1967 (372,793). There is no single authoritative source that accounts for the displaced Palestinian population.204 As such, estimates of the current size of Palestinian refugee and IDP population are based on 201 Palestinian Central Bureau of Statistics (PCBS), ‘Dr. Awad Presents a Brief on Palestinians at the End of 2021’ (PCBS, 30 December 2021) [hereinafter PCBS, Dr. Awad Brief] <https://www.pcbs.gov.ps/post.aspx?lang=en&ItemID=4150> accessed 3 October 2022. 202 See the definition of Palestinian refugees and IDPs in the Glossary of Terms. 203 There are 6.8 million Syrian UNHCR registered refugees and 6.9 million IDPs, see UNHCR, ‘Figures at a Glance’ (UNHCR, 16 June 2022) <https://www.unhcr.org/figures-at-a-glance.html>; World Vision, ‘Syrian refugee crisis: Facts, FAQs, and how to help’ (World Vision, 12 July 2022( <https://www.worldvision.org/refugees-news-stories/ syrian-refugee-crisis-facts> accessed 3 October 2022. 204 While UNRWA does have registration statistics, they do not claim to be, and should not be, taken as statistically sound or comprehensive demographic data as they are based on voluntary registration and its definition excludes many refugees that meet the 1951 Refugee Convention definition.