Ufology, sometimes written UFOlogy (US: /juːˈfɑːlədʒi/ or UK: /juːˈfɒlədʒi/), is the investigation of unidentified flying objects (UFOs) by people who believe that they may be of extraordinary origins (most frequently of extraterrestrial alien visitors). While there are instances of government, private, and fringe science investigations of UFOs, ufology is generally regarded by skeptics and science educators as an example of pseudoscience.

Ufology is a neologism derived from UFO (a term coined by Edward J. Ruppelt), and is derived from appending the acronym UFO with the suffix -logy (from the Ancient Greek -λογία (-logia)). Early uses of ufology include an article in Fantastic Universe (1957) and a 1958 presentation for the UFO "research organization" The Planetary Center.

The roots of ufology include the "mystery airships" of the late 1890s, the "foo fighters" reported by Allied airmen during World War II, the "ghost fliers" of Europe and North America during the 1930s, the "ghost rockets" of Scandinavia (mainly Sweden) in 1946, and the Kenneth Arnold "flying saucer" sighting of 1947. Media attention to the Arnold sighting helped publicize the concept of flying saucers. Publicity of UFOs increased after World War II, coinciding with the escalation of the Cold War and strategic concerns related to the development and detection (for example, the Ground Observer Corps) of advanced Soviet aircraft.

Official, government-sponsored activities in the United States related to ufology ended in the late 1960s following the Condon Committee report and the termination of Project Blue Book. Government-sponsored, UFO-related activities in other countries, including the United Kingdom, Canada, Denmark, Italy, and Sweden also ended. An exception to this trend is France, which maintains the GEIPAN program, formerly known as GEPAN (1977–1988) and SEPRA (1988–2004), operated by the French Space Agency CNES. On 14 September 2023, NASA reported the appointment, for the first time, of a Director of U.A.P. (known earlier as U.F.O.), identified as Mark McInerney, to scientifically and transparently study such occurrences.

Despite investigations sponsored by governments and private entities, ufology is not embraced by academia as a scientific field of study, and is instead generally considered a pseudoscience by skeptics and science educators, being often included on lists of topics characterized as pseudoscience as either a partial or total pseudoscience. Pseudoscience is a term that classifies arguments that are claimed to exemplify the methods and principles of science, but do not adhere to an appropriate scientific method, lack supporting evidence, plausibility, falsifiability, or otherwise lack scientific status.

Some writers have identified social factors that contribute to the status of ufology as a pseudoscience, with one study suggesting that "any science doubt surrounding unidentified flying objects and aliens was not primarily due to the ignorance of ufologists about science, but rather a product of the respective research practices of and relations between ufology, the sciences, and government investigative bodies". One study suggests that "the rudimentary standard of science communication attending to the extraterrestrial intelligence (ETI) hypothesis for UFOs inhibits public understanding of science, dissuades academic inquiry within the physical and social sciences, and undermines progressive space policy initiatives".

In 2021, astronomer Avi Loeb launched The Galileo Project, which intends to collect and report scientific evidence of extraterrestrials or extraterrestrial technology on or near Earth via telescopic observations. In Germany, the University of Würzburg is developing intelligent sensors that can help detect and analyze aerial objects in hopes of applying such technology to UAP. A 2021 Gallup poll found that belief among Americans in some UFOs being extraterrestrial spacecraft grew between 2019 and 2021 from 33% to 41%. Gallup cited increased coverage in mainstream news and scrutiny from government authorities as a factor in changing attitudes towards UFOs.

In 2022, NASA announced a nine-month study starting in the fall to help establish a road map for investigating UAP—or for reconnaissance of the publicly available data it might use for such research. In 2023, the RAND Corporation published a study reviewing 101,151 public reports of UAP sightings in the United States from 1998 to 2022. The models used to conduct the analysis showed that reports of UAP sightings were less likely within 30 km of weather stations, 60 km of civilian airports, and in more–densely populated areas, while rural areas tended to have a higher rate of UAP reports. The most consistent and statistically significant finding was that reports of UAP sightings were more likely to occur within 30 km of military operations areas, where routine military training occurs.