What are difference between the ELF symbol visibility levels?

The [NASM docs on *"elf Extensions to the GLOBAL Directive"* say,](https://www.nasm.us/doc/nasmdoc7.html) > Optionally, you can control the ELF visibility of the symbol. Just add one of the visibility keywords: default, internal, hidden, or protected. The default is default of course. Where are these defined? and how does ld use them? I see [access levels mentioned frequently in C++ which include *protected*, *public*, and *private*](https://en.cppreference.com/w/cpp/language/access) , but I don't know if this is what ELF is referencing? My use-case is C and Assembly so if you can make this relevant to those two languages and the linker, extra points.