ELF has two related concepts for managing symbols in your programs. The first concept is the symbol binding. Global binding means the symbol is visible outside the file being built; local binding is the opposite and keeps the symbol local only (static) and weak is like global, but suggests that the symbol can be overridden.

To combat this, ELF provides for visibility attributes. Symbols can be default, protected, hidden or internal. Using these attributes, we can flag extra information for the dynamic loader so it can know which symbols are for public consumption, and which are for internal use only.

The most logical way to use this is to make all symbols by default hidden with -fvisibility=hidden and then "punch holes in the wall" for those symbols you want visible.