Messages and Locales are used in localization of content.

messages.cpp

#include <iostream>
#include <locale>
int main()
{
    std::locale loc("de_DE");
    auto& facet = std::use_facet<std::messages<char>>(loc);
    const char* dir = "/usr/share/gcc-data/x86_64-pc-linux-gnu/4.6.1/locale";
    auto cat = facet.open("libstdc++", loc, dir);
    std::cout << "\"please\" in German: "
              << facet.get(cat, 0, 0, "please") << '\n'
              << "\"thank you\" in German: "
              << facet.get(cat, 0, 0, "thank you") << '\n';
    facet.close(cat);
}

/* Output
"please" in German: bitte
"thank you" in German: danke
*/