science

ISO 3166

ISO 3166 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand ISO 3166 rather than just read about it. In short: ISO 3166 is a standard published by the International Organization for Standardization (ISO) that defines codes for the names of countries, dependent territories, special areas of geographical interest, and their principal subdivisions (e.g., provinces or states). The official name of the standard is Codes for the representation of names of countries and their subdivisions.

Key takeaways

ISO 3166 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect ISO 3166 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of ISO 3166 from memory before moving on to harder problems.

Reference excerpt

ISO 3166 is a standard published by the International Organization for Standardization (ISO) that defines codes for the names of countries, dependent territories, special areas of geographical interest, and their principal subdivisions (e.g., provinces or states). The official name of the standard is Codes for the representation of names of countries and their subdivisions.

Parts It consists of three parts:

ISO 3166-1, Codes for the representation of names of countries and their subdivisions – Part 1: Country code, defines codes for the names of countries, dependent territories, and special areas of geographical interest. It defines three sets of country codes: ISO 3166-1 alpha-2 – two-letter country codes, which are the most widely used of the three, and used most prominently for the Internet's country code top-level domains (with a few exceptions). ISO 3166-1 alpha-3 – three-letter country codes, which allow a better visual association between the codes and the country names than the alpha-2 codes. ISO 3166-1 numeric – three-digit country codes, which are identical to those developed and maintained by the United Nations Statistics Division, with the advantage of script (writing system) independence, and hence useful for people or systems using non-Latin scripts. ISO 3166-2, Codes for the representation of names of countries and their subdivisions – Part 2: Country subdivision code, defines codes for the names of the principal subdivisions (e.g., provinces, states, departments, regions) of all countries coded in ISO 3166-1. ISO 3166-3, Codes for the representation of names of countries and their subdivisions – Part 3: Code for formerly used names of countries, defines codes for country names which have been deleted from ISO 3166-1 since its first publication in 1974.

Editions The first edition of ISO 3166, which included only alphabetic country codes, was published in 1974. The second edition, published in 1981, also included numeric country codes, with the third and fourth editions published in 1988 and 1993 respectively. The fifth edition, published between 1997 and 1999, was expanded into three parts to include codes for subdivisions and former countries.

ISO 3166 Maintenance Agency The ISO 3166 standard is maintained by the ISO 3166 Maintenance Agency (ISO 3166/MA), located at the ISO central office in Geneva. Originally it was located at the Deutsches Institut für Normung (DIN) in Berlin. Its principal tasks are:

To add and to eliminate country names and to assign code elements to them; To publish lists of country names and code elements; To maintain a reference list of all country code elements and subdivision code elements used and their period of use; To issue newsletters announcing changes to the code tables; To advise users on the application of ISO 3166.

Members There are fifteen experts with voting rights on the ISO 3166/MA. Nine are representatives of national standards organizations:

Association française de normalisation (AFNOR) – France American National Standards Institute (ANSI) – United States British Standards Institution (BSI) – United Kingdom Deutsches Institut für Normung (DIN) – Germany Japanese Industrial Standards Committee (JISC) – Japan Standards Australia (SA) – Australia Kenya Bureau of Standards (KEBS) – Kenya Standardization Administration of China (SAC) – China Swedish Standards Institute (SIS) – Sweden The other six are representatives of major United Nations agencies or other international organizations who are all users of ISO 3166-1:

International Atomic Energy Agency (IAEA) International Civil Aviation Organization (ICAO) International Telecommunication Union (ITU) Internet Corporation for Assigned Names and Numbers (ICANN) Universal Postal Union (UPU) United Nations Economic Commission for Europe (UNECE) The ISO 3166/MA has further associated members who do not participate in the votes but who, through their expertise, have significant influence on the decision-taking procedure in the maintenance agency.

Codes beginning with "X" Country codes beginning with "X" are used for private custom use (reserved), never for official codes. Despite the words "private custom", the use may include other public standards. ISO affirms that no country code beginning with X will ever be standardised. Examples of X codes include:

The ISO 3166-based NATO country codes (STANAG 1059, 9th edition) use "X" codes for imaginary exercise countries ranging from XXB for "Brownland" to XXY for "Yellowland", as well as for major commands such as XXE for SHAPE or XXS for SACLANT. X currencies defined in ISO 4217.

Current country codes

Worked examples

Example 1 — a first encounter with ISO 3166

Start with the simplest possible case. Write down what ISO 3166 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to ISO 3166 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about ISO 3166 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of ISO 3166

In research: ISO 3166 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses ISO 3166 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: ISO 3166 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1974 establishments, 1974 introductions, ISO 3166, so understanding it makes those chapters shorter.
In everyday life: Look for ISO 3166 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “ISO 3166” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study ISO 3166 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ISO 3166 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain ISO 3166 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ISO 3166 in simple terms?

Why does ISO 3166 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study ISO 3166?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on ISO 3166.