en.wikipedia.org/wiki/GObject

This is incorrect because GLib uses odd minor numbers for development series, not stable releases. In the official gversionmacros.h.in file, GLib states that during an unstable development cycle, GLIB_VERSION_CUR_STABLE evaluates to the next stable (unreleased) version. The macro logic checks GLIB_MINOR_VERSION % 2, which means odd minor versions such as 2.87 are treated as development-cycle versions, not stable ones.

The GNOME download archive confirms that glib-2.87.0 was released on 2025-11-03, and that the next even-minor series, 2.88.0, was released later on 2026-03-16. So 2.87.0 was a real release, but it was part of the unstable 2.87 development series rather than a stable release.

The official GObject Introspection overview defines GObject introspection as the middleware layer between C libraries and language bindings. It then separately says the GI project includes “an XML format called GIR”. In other words, GIR names the XML metadata format, not the middleware layer itself.

So the article’s wording is backwards: GObject Introspection is the project/system, while GIR is one of its file formats.