Data Sources & Methodology

Every fact on CountryExplainer comes from a named data source. This page lists those sources, their licences and how often we refresh them. Pages that change often — visa rules, travel advice, airport services — also show the date of the last check.

Visa and entry requirements

Source: TravelRequirements.info — Entry Requirements Dataset, AXG Sp. z o.o. (CC BY 4.0), with gaps filled from the open Passport Index dataset (MIT). Official government sources are linked on each destination and passport page.

Updated: automatically every day. Each page shows when the rule was last checked at the source and when we last synced it.

Travel safety

Source: US Department of State travel advisories (public domain) and UK FCDO foreign travel advice (Open Government Licence v3.0). Our safety rating combines both governments' advice; it does not add our own assessment.

Updated: automatically every day.

Weather and the best time to visit

Source: NASA POWER — monthly temperature, rainfall and humidity averaged over 25 years for each country. The "best months" are calculated from these averages with one rule applied to every country.

Country facts, population and economy

Sources: CIA World Factbook (public domain) for geography, capitals, borders, independence and government; World Bank Open Data (CC BY 4.0) for population, GDP, price levels, life expectancy and education; samayo/country-json (MIT) for some country lists.

Updated: when the sources publish new annual figures. The year of each figure is shown where it matters.

Languages

Source: Languages of the World dataset (MIT) — ISO 639-3, Glottolog (CC BY 4.0), Unicode CLDR, Google LinguaMeta (CC BY 4.0) and Wikidata. Speaker numbers mix first- and second-language speakers and differ between sources.

Practical travel information

• Plug types, voltage, emergency numbers and International Driving Permits: English Wikipedia (CC BY-SA).
• Speed limits and drink-driving limits: OpenStreetMap wiki default speed limits (CC BY-SA 2.0) and the WHO Global Health Observatory.
• Public holidays: Nager.Date public holiday database and the vacanza/holidays library (both MIT).
• Exchange rates: daily reference rates from the open-source currency-api (CC0).

Airports, aircraft and places

• Airports: OurAirports (public domain).
• Aircraft: What is flying? database (ODbL 1.0).
• Ski resorts: OpenSkiMap — © OpenStreetMap contributors and Skimap.org (ODbL 1.0).
• National parks: Wikidata (CC0), English Wikipedia and Wikimedia Commons (photo authors are credited on each park page).
• Cities and coordinates: GeoNames (CC BY 4.0).

Rankings

• CO₂ emissions: Our World in Data, based on the Global Carbon Budget and Jones et al. (CC BY 4.0).
• Military strength: Global Firepower military strength ranking and World Bank / SIPRI military expenditure data (CC BY 4.0).
• Other rankings are calculated from the sources above; each ranking page names its source and method.

Airport services (Meet & Greet, lounges, transfers)

Services, prices and availability come from our booking partner and are refreshed every day. The final price is confirmed at checkout.

News

Our travel news is based on published reports about visas, entry rules, airports and travel safety. How we write and check it is explained in our editorial policy.

Found a mistake?

Rules change and sources can be wrong. If you spot an error, email [email protected] with the page address — we check every report and correct confirmed errors.