Are surrogate characters the same as supplementary characters?

This question shows a common confusion. It is very important to distinguish surrogate code points (in the range U+D800..U+DFFF) from supplementary code points (in the completely different range, U+10000..U+10FFFF). Surrogate code points are reserved for use, *in pairs*, in representing supplementary code points in UTF-16.

There are supplementary characters (i.e. encoded characters represented with a single supplementary code point), but there are not and will never be *surrogate characters* (i.e. encoded characters represented with a single surrogate code point).