"extensible language"

why exactly is c++ referred to as an extensible language?

Because libraries can be added to the standard, there by extending its functionality.

Consider the Standard Template Library; There was a time in C++ where there was no standard vector container or many of the other containers and features of the STL.

That makes sense, I didn't even think of that *smacks forehead* DOH! lol. Thanks a bunch, I appreciate your help