Grade Point Average (GPA)?

What are the GPA for academic, Pre-AP, AP, GT & Honor cles? How do you calculate your GPA? The average grade of all my grades on the end of school? The average GPA of all my cles on the end of the school? Does college only see one GPA from each year of school or do they see all my grades? What is a good GPA for college? Does anyone see my PSAT scores or just me? Did they change the GPA policy?