The formats people meet every day are historical survivors. ZIP was introduced by PKWARE in 1989. JPEG’s first standard was published in 1992. Adobe introduced PDF in 1993, and PDF later became an ISO standard. PNG was designed in the mid-1990s and documented by the W3C. The Office Open XML family was standardized through Ecma in 2006. Those dates are milestones, not birthdays for a single unchanging object.

Why do several decades fit in one file?

A format acquires an installed base. Once operating systems, browsers, office suites, archives, and production tools can read it, compatibility becomes a feature that a technically superior newcomer has to overcome. A new format must offer enough improvement to pay for conversion, retraining, support, and the risk that someone else cannot open the result.

What changes after standardization?

A company can publish a format and still control important tools around it. A standards body can make the rules easier to inspect and implement, but a standard is not automatically universal. Profiles and extensions continue to appear because industries need details that the base document left open. The familiar file is therefore both a technical design and a social bargain.

Why do dates mislead?

A publication date identifies a milestone, not the moment a format became ordinary. A browser, camera, archive, or office may adopt it years later, and different implementations may support different features. The relevant history is a chain: specification, tools, distribution, and the point at which other people could reasonably be expected to read the result.

Adoption can also be uneven inside one format. A tool may read an older profile but fail on a newer feature, or an archive may preserve the standard while losing the software that gave it practical meaning. A date starts the investigation; it does not finish it.

The dates also explain why “old” does not mean “finished.” JPEG has accumulated profiles and implementations; PDF has gained features and preservation variants; ZIP remains a container inside newer formats. The bytes survive because the surrounding ecosystem keeps translating old agreements into new software.

The short head looks timeless because old agreements keep working. The long tail is where the abandoned versions, specialist profiles, and migration problems remain visible.