What is the effect of extern "C" in C++?

What is the effect of extern "C" in C++?

c++ c linkage name-mangling extern-c

c

Determining C executable name

c gcc compilation executable linkage

c

What does mean for a name or type to have a certain language linkage?

c++ c standards linkage extern-c

c

External, internal and no linkage or why this does not work?

c language-lawyer linkage

c

Difference between internal and no linkage

c++ c scope linkage

c