Military pay charts

Go to this website, https://www.militaryrates.com/military-pay-charts, and read it over. This is a recent set of Military Pay Charts. Answer the questions from the charts below: 1. What are the three general categories of rank, according to the site? 2. How many pay grades do they have (in total), according to the chart? 3. Are the pay grades different by categories of rank? If so, why is that the case? 4. According to the chart, how would a person increase their pay grade in the military?