Doxygen Warning: ignoring unknown tag

Using Doxygen to generate documentation. Getting "Warning: ignoring unknown tag" errors, and I can't see why.

Minimal, Complete, and Verifiable example:

/** This is a test */
#include <iostream>

/** \fn foo */
int foo() {
    return 0;
}

int main() {   
    std::cout << "hello world" << std::endl;
    return 0;
}

Errors:

[53]: doxygen .\myTest.cpp
Warning: ignoring unknown tag `This' at line 1, file .\myTest.cpp
Warning: ignoring unknown tag `is' at line 1, file .\myTest.cpp
Warning: ignoring unknown tag `a' at line 1, file .\myTest.cpp
Warning: ignoring unknown tag `test' at line 1, file .\myTest.cpp
Warning: ignoring unknown tag `fn' at line 4, file .\myTest.cpp
Warning: ignoring unknown tag `foo' at line 4, file .\myTest.cpp
Warning: ignoring unknown tag `int' at line 5, file .\myTest.cpp
Warning: ignoring unknown tag `foo' at line 5, file .\myTest.cpp
Warning: ignoring unknown tag `return' at line 6, file .\myTest.cpp
Warning: ignoring unknown tag `0' at line 6, file .\myTest.cpp
Warning: ignoring unknown tag `int' at line 9, file .\myTest.cpp
Warning: ignoring unknown tag `main' at line 9, file .\myTest.cpp
Warning: ignoring unknown tag `std' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `cout' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `hello' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `world' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `std' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `endl' at line 10, file .\myTest.cpp
Warning: ignoring unknown tag `return' at line 11, file .\myTest.cpp
Warning: ignoring unknown tag `0' at line 11, file .\myTest.cpp
Searching for include files...
Searching for example files...
Searching for images...
Searching for dot files...
Searching for files to exclude
Searching for files to process...
...other stuff...

Thx, Sincerely, Keith :^)