"A2" (Elementary) is the second level, as defined by the European Common Framework, which is used on this Chinese Pronunciation Wiki. It is roughly equivalent to HSK Level 2. For more information on the levels used here, see the Pronunciation Points by Level page. There are 3 total pronunciation points in the list below.
||Tone change rules
||If you know all 4 tones (plus the neutral tone), then it's time to learn the three big rules about when these tones regularly change.