Purchasing Power Parity (PPP)

Thanks to tutor2u for this summary
http://www.tutor2u.net/economics/blog/the-purchasing-power-parity-ppp-exam-skills?utm_medium=email&utm_campaign=Economics%20daily%20digest%20Fri%2020th%20May%202016&utm_content=Economics%20daily%20digest%20Fri%2020th%20May%202016+CID_11d26065ecc1a084451aeb110c7b8403&utm_source=CampMonitor&utm_term=The%20Purchasing%20Power%20Parity%20PPP%20-%20Exam%20skills%20With%20the%20unit%202%20and%20theme%202%20exams%20approaching%20it%20is%20essential%20to%20have%20some%20background%20on%20the%20usefulness%20of%20PPP%20when%20comparing%20GDP%20between%20countries