Shared libraries have a special name called the "soname'' which consists of the prefix "lib'', the name of the library, ".so'', followed by a period and a major version number that is incremented whenever the library APIs change.

Shared libraries also has a "real name'', which is the name of the file containing the actual library code. The real name is the soname followed by a period and a minor number, optionally followed by another period and a release number. Generally a fully qualified soname is simply a symbolic link to the real name.

For more information, look at the Linux Standard Base specifications.