What is the IEC and how does it relate to ISO?

IEC = International Electrotechnical Commission, the international body for electrical, electronic, and related-technology standards. Joint ISO/IEC standards (like 27001) live in both organisations' catalogues.

The IEC and ISO split the world of standardisation between them. ISO covers everything except pure electrical engineering; the IEC owns the electrical and electronic domain. The reason IT-security standards carry both prefixes (ISO/IEC 27001) is historical: when computing emerged, it straddled both worlds — neither body wanted to surrender it — so they govern it jointly through ISO/IEC JTC 1 (Joint Technical Committee 1 for IT). That is why you should read "ISO/IEC" not as a single brand but as two international bodies sharing authorship of one document.

Key facts:

• Founded 1906 in London, moved to Geneva in 1948.
• Like the ISO, the IEC is a Verein nach Schweizer Recht (Swiss-law non-profit association); member countries are represented by national bodies.
• IEC standards live in number ranges 60000–79999.
• Joint ISO/IEC examples: 27001 (ISMS), 15408 (Common Criteria), 7816 (smartcards).

Tip: "ISO/IEC 27001" is not a co-ordinated name change; it's literally that two international bodies share authorship and revenue from the standard.

Go deeper:

• International Electrotechnical Commission (Wikipedia) — the IEC's scope and why joint ISO/IEC standards carry both acronyms via JTC 1.