Unicode collation algorithm

When used with the default Unicode collation element table (DUCET),
this collation method is similar to the European ordering rules for
strings in most European languages. In particular, for strings in the Latin alphabet, the ordering is the same as normal sorting order in English and similar languages, since it first looks only at letters stripped of any modifications or diacritical marks.

Note - this is complicated stuff and this description may be in error. It is better to look at the Unicode Technical Standard #10 itself.

In addition to specifying a default sorting, UTS #10 also specify how tailorings are used to get any desired sorting behaviour for a locale.

An important open source implementation of UCA is included with the IBM International Components for Unicode, which also supports tailoring. You can see the effects of tailoring and a large number of language specific tailorings in the on-line
ICU Locale Explorer.

See also