POD is an acronym in C++ that means plain old data. It is a class/struct that ONLY has member variables and no methods, constructors, destructors, virtual functions, etc. For example,
Example
#include<iostream>
using namespace std;
// POD
struct MyStruct {
int key;
string data;
};
int main() {
struct MyStruct s;
s.key = 1;
s.data = "hello";
return 0;
}The struct MyStruct has no user-defined ctor, dtor, etc and hence is a POD.