It doesn't, strictly speaking, and in fact, it barely does. It's usually just a symlink from libwhatever.latest.version.number to libwhatever.so, on the theory

It doesn't, strictly speaking, and in fact, it barely does. It's usually just a symlink from libwhatever.latest.version.number to libwhatever.so, on the theory that you probably want the latest version of the library (with all its improvements and bugfixes). There's sometimes an intermediate symlink to the newest major versions too (libwhatever.latest.so, libwhatever.2.so), to avoid breaking changes.